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THE  BODY 
M  HEALTH 


O'SHEAanJKELLOCIl 

HEALTH  SERIES 
FHYSIOLOOYmf 


BIOLOGY 

LIBRARY 

G 


f 

THE   HEALTH    SERIES 

OF 

PHYSIOLOGY  AND   HYGIENE 


THE    BODY    IN    HEALTH 


THE   HEALTH    SERIES 

OF 

PHYSIOLOGY  AND    HYGIENE 


HEALTH   HABITS 
HEALTH   AND    CLEANLINESS 

THE   BODY   IN   HEALTH 
MAKING   THE    MOST   OF   LIFE 


i"Y;--"i  /'      -'-A""'! 
THE    H EA  LT  H  1  3 ER IES 

OF 

PHYSIOLOGY  AND    HYGIENE 


THE  BODY   IN   HEALTH 


BY 


M.    V.    O'SHEA 

PROFESSOR   OF    EDUCATION,    UNIVERSITY   OF   WISCONSIN 
AUTHOR   OF   "DYNAMIC   FACTORS  IN   EDUCATION,"   ETC. 

AND 


J.    H.    KELLOGG 


SUPERINTENDENT  OF  THE  BATTLE  CREEK  SANITARIUM 
AUTHOR  OF  "MAN,  THE  MASTERPIECE,"  ETC. 


gorfe 
THE   MACMILLAN   COMPANY 

1921 

All  rights  reserved 


0 


BIOLOGY 

LIBRARY 

G 


COPYRIGHT,  1915, 
BY  THE  MACMILLAN   COMPANY. 


Set  up  and  electrotyped.     Published  February,  1915. 


Nortoooti 

J.  8.  Gushing  Co.  —  Berwick  &  Smith  Co. 
Norwood,  Mass.,  U.S.A. 


INTRODUCTION 

IT  is  the  aim  in  "  The  Health  Series  of  Physiology  and 
Hygiene  "  to  present  in  an  attractive  form  for  pupils  in  the 
elementary  school  the  latest  and  most  accurate  knowledge 
relating  to  physiology,  and  especially  to  the  hygiene  of 
daily  life.  The  constant  effort  of  the  authors  has  been  to 
make  scientific  knowledge  so  simple,  so  concrete,  and  so 
captivating  that  pupils  can  hardly  fail  to  take  an  interest 
in  the  problems  of  preserving  health  for  the  purpose  of 
making  the  most  of  life. 

Throughout  the  series,  the  aim  has  been  kept  in  view 
of  awakening  in  the  young  a  normal  desire  to  live  in 
such  a  manner  as  to  develop  strength  and  preserve  health, 
because  in  this  way  the  individual  will  have  the  greatest 
success  in  securing  the  things  which  he  desires,  and  in 
avoiding  the  disabilities  and  pains  which  otherwise  are 
likely  to  occupy  a  considerable  part  of  his  life.  Compara- 
tively little  attention  is  given  to  anatomy,  and  only  suffi- 
cient physiology  is  presented  to  constitute  a  basis  for  the 
facts  of  health  which  are  discussed. 

Very  extensive  use  is  made  of  photographs  and  diagrams 
illustrating  every-day  life  in  the  city  and  in  the  country. 
There  is  at  least  one  interesting  and  practical  original 
exercise  suggested  for  every  principle  of  health  presented 


!•*  O  f\  /"*  «-v 


vi  INTRODUCTION 

in  any  lesson,  and  it  is  the  plan  that  each  pupil  should 
work  out  each  exercise  and  report  upon  it  during  the  reci- 
tation period.  In  order  further  to  assist  the  teacher  and 
the  pupil,  a  list  of  questions,  fully  covering  the  text,  has 
been  given  at  the  end  of  each  chapter. 


PREFACE 

EVERY  one  would  like  to  have  a  good,  vigorous,  well- 
poised  body,  free  from  aches  and  pains  and  fit  for  any  kind 
of  work  or  pleasure.  How  can  one  develop  and  maintain 
his  body  in  this  condition  ?  The  Third  Book  of  the 
Health  Series  is  designed  to  answer  this  question.  First, 
it  is  shown  how  habits  of  living  will  affect  stature,  sym- 
metry, strength,  and  poise  of  the  body.  Much  attention 
is  given  to  the  problem  of  how  to  keep  the  vital  organs 
in  good  working  order  so  that  they  can  destroy  the  ene- 
mies of  the  body  and  furnish  energy  for  all  the  work  one 
wants  to  do.  When  one  does  not  feel  fit  for  the  work 
he  has  to  do,  what  may  be  the  cause  ?  This  question  is 
discussed  in  detail  also.  In  a  concrete,  practical  manner, 
suggestions  based  upon  a  great  deal  of  investigation  as  well 
as  experience  are  made  in  respect  to  the  sort  of  exercise 
which  will  be  best  for  different  people  and  different  pur- 
poses, how  one  may  increase  his  endurance,  and  what  kind 
of  habits  will  reduce  one's  capacity  to  do  work  without 
fatigue. 

A  person  cannot  keep  in  fit  condition  without  giving 
heed  to  what  and  how  he  eats  and  drinks ;  and  these  mat- 
ters are  considered  in  detail.  Many  people  deliberately 
handicap  themselves  in  the  race  of  life,  though  they  may 


viii  PREFACE 

not  be  aware  of  what  they  are  doing.  They  take  into 
the  body  things  which  lessen  their  courage,  ambition,  and 
working  power,  so  that  they  lose  out  in  competition  with 
others  who  avoid  these  bodily  enemies.  This  book  goes 
into  all  these  matters  in  a  simple,  concrete  way.  Topics 
concerning  the  elimination  of  poisons  from  the  system, 
helping  the  body  to  repair  itself  when  it  becomes  worn,  and 
fortifying  it  so  that  it  can  defend  itself  against  attacks  from 
without  as  well  as  from  within,  are  given  a  prominent  place 
in  the  book.  One  cannot  have  the  kind  of  body  he  desires, 
so  that  he  can  get  the  most  out  of  life,  unless  the  mind 
as  governor  of  the  body  is  properly  trained  and  kept  in 
a  condition  of  health  and  poise,  so  this  subject  is  treated 
herein. 

The  authors  of  the  Health  Series  believe  that  one  of  the 
best  ways  to  impress  facts  of  health  is  to  present  them  to 
the  eye  in  photographs  and  drawings.  So  this  book  is 
fully  illustrated  with  pictures  made  especially  for  this  pur- 
pose. As  an  aid  to  teacher  and  pupils,  each  topic  discussed 
is  indicated  in  a,  marginal  heading.  The  authors  further 
believe  that  in  order  to  get  the  most  out  of  their  study 
of  hygiene,  pupils  should  apply  principles  of  health  in  their 
every-day  life,  and  so  the  authors  have  given  at  the  end 
of  each  chapter  a  number  of  problems  relating  to  health. 
It  is  expected  that  each  pupil  will  work  these  out  and 
discuss  them  in  class.  Lastly,  a  detailed  list  of  review 
questions  is  added  to  each  chapter,  and  an  index  is  given 
at  the  close  of  the  book. 


CONTENTS 


CHAPTER 

I.  THE  LITTLE  WORKERS  OF  THE  BODY  . 

II.  THE  MAINTENANCE  OF  THE  BODY 

III.  How  FOOD  BECOMES  LIVING  TISSUE  „ 

IV.  EATING  FOR  HEALTH  AND  PLEASURE  . 

V.  THE  BLOOD 

VI.  PURE  BLOOD  AND  A  SOUND  HEART 

VII.  THE  BREATH  OF  LIFE 

VIII.  How  THE  BODY  CLEANSES  ITSELF 
IX.  How  THE  TEMPERATURE  OF  THE  BODY  is  REGU- 
LATED       

X.  THE  FRAMEWORK  OF  THE  BODY   .... 

XI.  THE  BODY  IN  MOTION 

XII.  FEELING  AND  THINKING        ..... 

XIII.  GATEWAYS  OF  THE  MIND  —  SIGHT 

XIV.  GATEWAYS  OF  THE  MIND  —  HEARING  . 

XV.    GATEWAYS  OF  THE  MIND  —  TOUCH,  TASTE,  AND 

SMELL 

XVI.    THE  BODY'S   ENEMIES  —  ALCOHOL  AND  TOBACCO 
XVII.    THE  BODY'S  ENEMIES  —  DISEASE  GERMS 
XVIII.     "CATCHING"  DISEASES         .        .        . 

APPENDIX  —  TABLES  OF  COMPOSITION  OF  FOODS   . 

GLOSSARY 

INDEX . 

ix 


PAGE 

I 

15 

33 
58 
74 

100 

H3 
141 

155 
173 
191 
205 
228 
248 

259 
269 
280 
294 


325 


THE  BODY  IN  HEALTH 

CHAPTER   I 
THE  LITTLE  WORKERS  OF  THE  BODY 

IF  you  look  at  a  house  from  a  distance,  you  can  see 
only  its  general  form  and  outline.  As  you  come  closer 
to  it,  you  can  see  distinctly  the  bricks  of  which  the 
house  is  made.  You  discover  then  that  the  house, 
instead  of  being  just  one  object,  is  made  up  of  a 
number  of  smaller  ones. 

Like  the  house,  the  human  body  is  composed  of 
many  small  parts.  The  tiny  living  bricks  of  which 
the  body  is  built  are  called  cells.  These  cells  are  so 
small  that  they  cannot  be  seen  at  all  by  the  "naked 
eye."  When  we  examine  a  piece  of  flesh  under  a 
microscope,  we  see  that  it  is  made  up  of  separate, 
distinct,  perfectly  formed,  and  exceedingly  small  parts. 
Though  these  parts  differ  greatly  in  shape,  color,  and 
use,  they  are  all  cells. 

All  living  things,  both  vegetable  and  animal,  are 
composed  of  cells.  Things  that  have  no  life,  such  as 
stones,  water,  and  air,  are  not  made  of  cells.  But 
everything  that  lives,  animal  as  well  as  vegetable,  is 
made  up  of  wonderful  tiny  cells. 


2  THE   BODY  IN  HEALTH 

There  are  some  minute  animals  which  consist  of 
just  a  single  cell.  The  amoeba^  found  in  ditch  water 
and  stagnant  pools,  is  a  good  sample  of  a  single-celled 
animal.  It  will  be  easy  for  you  in  the  summer  time 
to  get  specimens  of  the  amoeba  for  study  from  a  ditch 
or  pond.  Of  course,  you  will  have  to  use  a  good  micro- 
scope. Why?  In  winter,  a  small  pond  may  be  ar- 
ranged by  putting  some  hay  in  a  saucer  with  hydrant 
water  and  setting  it  away  for  two  or  three  weeks  in  a 


THE     AMCEBA     MANY    TIMES     ENLARGED.       IN     FORMING   NEW   AMCEBJE   THE    MOTHER 
CELL    SIMPLY  DIVIDES    INTO   TWO   NEW   CELLS. 

warm  place.     A  little  fresh  water  must  be  added  daily 
to  take  the  place  of  that  which  evaporates. 

This  minute,  one-celled  animal,  seen  under  the 
microscope,  looks  much  like  a  small  drop  of  jelly.  It 
has  no  mouth,  yet  it  can  eat.  It  spreads  itself  over 
or  around  a  particle  of  food  and  absorbs  it,  just  as 
water  flowing  down  a  pane  of  glass  may  pick  up  par- 
ticles of  dust.  It  has  no  limbs,  yet  it  moves  easily 
and  rapidly  from  place  to  place.  It  stretches  itself 
out  in  the  direction  it  wishes  to  travel  and  draws 


THE   LITTLE  WORKERS  OF  THE   BODY       3 


itself  along  like  a  worm  from  place  to  place,  contin- 
ually changing  its  form.  It  eats,  breathes,  works, 
and  rests.  This  wonderfully  simple  and  fragile  little 
cell  is  just  as  clearly  and  distinctly  an  animal  as  is  a 
horse,  an  elephant,  or  a  man  Yet  it  is  so  minute 
that  it  takes  eight  hundred  and  fifty  amoebae  arranged 
side  by  side  to  make  a  row  an 
inch  long ;  and  one  hundred  can 
swim  about  in  a  drop  of  liquid 
which  would  hang  on  the  point  of 
a  pin. 

Where  do  the  cells  of  which  all 
living  things  are  formed  come  from  ? 
Every  cell  comes  from  another  cell.    A  DIAGRAM  OF  A  CELL 
How  are  they  formed  ?     They  are 
formed  by  the  dividing  of  each  cell 

7  into  two  new  cells,  as  you  see 
in  the  picture,  and  the  process 
goes  on  until  millions  of  cells  are 
formed. 

When  you  examine  the  jelly- 
like  mass  of  the  amoeba  under 
the  microscope,  you  see  HOW  the 

in   it   a   dense,    grayish  cells  are 

THIS  SHOWS  THE  NUCLEUS  (£)     portion,    which    is    the  formed- 

nucleus  of  the   cell.     When   the 

cell  is  preparing  for  division,  the  nucleus  divides  and 
part  of  it  goes  to  each  end  of  the  cell.  A  wall  is  then 
formed  across  the  middle  of  the  cell,  and  it  separates 


MADE      TO      SHOW      THE 
NUCLEUS    ESPECIALLY. 


THE   BODY  IN  HEALTH 


into  two  parts.  Each  part  is  a  complete  new  cell, 
having  its  own  nucleus.  When  a  single-celled  animal 
divides  in  this  way,  each  of  the  new  cells  forms  a 
complete  new  animal,  which  grows  to  the  size  of  the 
parent. 

The  bodies  of  animals  larger  than  the  amoeba,  in- 
stead of  being  formed  of  a  single  cell,    may  be  made 

up  of  millions  of  cells, 
each  one  of  which  is 
quite  as  much  an  in- 
dependent living  be- 
ing as  is  the  amoeba. 
Each  animal  body  be- 
gins with  a  single  cell ; 
but  when  this  divides, 
the  cells  do  not  sepa- 
rate and  live  alone,  as 
in  the  case  of  the 
single-celled  animals. 

NOTICE  HOW  THE  MOTHER  CELL  DIVIDES  TO         1  hey  remain    together 

and  keep  on  dividing 
and  dividing  until  there 
may  be  many  millions  of  them,  a  great  colony,  all 
living  together  and  working  for  the  good  of  each. 

The  body  might  be  compared  to  a  swarm 
colonies  of  bees,  only  that  in  the  case  of  the  bees  each 
one  may  live  for  some  time  separate  from  the 
rest  if  he  chooses  to  do  so.  This  is  true  to  a 
small  extent  of  the  cells  of  which  animals  and  plants 


FORM  NEW  CELLS,  AND  THEN  UNITES  INTO 
COLONIES. 


or  com- 
munities. 


THE  LITTLE  WORKERS  OF  THE   BODY       5 

are  composed.  When  a  portion  is  cut  from  a 
plant  or  animal,  its  cells  do  not  always  die  at  once. 
The  legs  of  a  frog  will  twitch  and  kick  after  they  are 
severed  from  its  body.  The  heart  of  a  turtle  will 
continue  to  beat  for  hours  after  its  head  has  been  cut 
off.  When  some  kinds  of  worms  are  cut  in  two 
each  part  will  live  and  grow  into  a  complete  worm. 
A  flower  stem  cut  from  a  plant  will  continue  to  live 
and  bloom  for  days  in  water.  A  branch  cut  from  the 
parent  tree  and  stuck  in  the  ground  may  even  grow 
into  a  new  tree.  This  is  because  each  part,  being  made 
up  of  separate  little  living  beings,  has  its  own  life. 

For  this  reason  it  is  possible  to  remove  a  portion  of 
one  animal  and  graft  it  upon  another  animal  of  the 
same  kind.  In  the  ordinary  process  of  grafting  fruit 
trees,  a  bud  of  one  tree  is  planted  in  a  little  slit  cut  in 
the  bark  of  another  tree.  When  the  work  is  well  done, 
the  bud  soon  becomes  accustomed  to  its  new  home 
and  grows  and  bears  fruit  and  leaves  like  its  parent. 

In  somewhat  the  same  manner,  surgeons  sometimes 
take  portions  of  skin  from  -one  or  several  persons  to 
graft  upon  another  person  who  has  lost  by  burning 
or  some  other  accident  large  portions  of  skin.  Many 
cases  have  occurred  in  which  a  portion  of  a  finger, 
when  cut  off,  has  been  replaced  and  has  grown  secure. 
Surgeons  often  graft  in  portions  of  bone  to  repair 
diseased  or  injured  limbs,  and  Dr.  Curel  of  the  Rocke- 
feller Institute  has  successfully  transplanted  kidneys 
and  other  organs.  Organs  and  tissues  may  be  kept 


6  THE   BODY  IN  HEALTH 

alive  for  months  after  removal  from  the  body,  and 
certain  tissues  may  be  made  to  grow. 

The  human  body  may  well  be  compared  to  a  com- 
munity made  up  of  multitudes  of  individuals.  There 
are  no  idlers  in  this  community ;  all  the  cells 
human  are  active  workers.  In  most  communities 
body  a  there  are  different  classes  of  workers,  such  as 
com".  merchants,  blacksmiths,  chemists,  bakers.  In 

mumty. 

the  body,  likewise,  there  is  a  division  of  labor. 
Some  cells  build,  others  tear  down.  Some  may  be 
compared  to  artists  ;  and  others,  to  scavengers  ;  that  is, 
there  are  cells  which  work  to  keep  the  body  clean  and 
healthy.  Some  make  different  kinds  of  fluids  to  be 
used  in  the  body.  There  are  cells  that  stand  as  sen- 
tinels to  give  the  body  warning  of  danger,  and  others 
that  are  little  soldiers  who  defend  it  against  the 
enemies  of  life  and  health. 

In  the  building  of  a  house  different  sets  of  workmen 
are  employed  for  the  different  parts :  bricklayers  for 
Ceil  laying  tne  brick  walls ;  carpenters  for  the 

structures  doors  and  other  woodwork ;  plumbers  for 
or  tissues.  ^  drainage  pipes;  and  so  on.  In  like 
manner,  the  little  cell  builders  form  themselves  into 
groups  for  building  up  the  different  structures  needed 
in  the  body.  The  different  kinds  of  cell  structures 
are  called  tissues.  A  large  part  of  the  work  of  the 
cells  is  to  build  and  repair  these  living  tissues  of  which 
the  body  is  composed. 

Some  of  the  cells  form  long,  white,  thread-like  fibers, 


THE  LITTLE  WORKERS  OF  THE   BODY 


very  tough  and  unyielding.  This  white  fibrous  tissue 
is  needed  to  bind  the  different  parts  of  the  body  to- 
gether and  to  make  cords  and  protective  coverings. 
There  is  also  a  yellow  elastic  tissue,  which  may  be 
stretched  like  India  rubber. 

The  yellow  elastic  tissue  and  the  fibrous  tissue  to- 
gether form  in  all   parts  of  the  body  a  marvelously 


WHITE  FIBROUS  TISSUE. 


YELLOW  FIBROUS  TISSUE. 


CELLS  IN  MUS- 
CULAR TISSUE. 
n,  nucleus. 


strong  though  elastic  structure,  a  finely  woven  mesh- 
work  called  connective  tissue.  This  binds  the  tissues 
together,  forms  sheaths,  membranes,  bands,  pouches, 
and  coverings,  and  serves  everywhere  for  purposes  of 
protection  and  support. 

The  meshes  of  the  connective  tissue  network  are 
in  some  parts  of  the  body  occupied  by  cells  filled  with 
fat.  This  soft  adipose  tissue,  as  it  is  called,  rounds 
out  the  form,  forms  cushions  for  delicate  organs  like 
the  eye,  and  serves  other  useful  purposes. 


8 


THE   BODY  IN   HEALTH 


Other  groups  of  cells  form  what  is  called  muscular 
tissue  by  which  all  sorts  of  movements  are  made.  This 
is  made  up  of  minute  fibers  which  shorten  and  lengthen 
much  as  an  earthworm  contracts  and  extends  its  body 
in  motion. 

The  hardest  of  the  tissues  which  the  cells  build  up 
in  the  body  is  called  bone  or  osseous  tissue,  which  is 

stronger  than  the  tough- 
est oak.  The  bones 
serve  as  supports  for 
the  body  and  as  levers 
by  means  of  which  it  is 
moved  about  by  the 
muscles. 

Something    like    the 
bone  tissue,  but  softer, 
e    and  capable  of  bending 

a,  group' or  two  cartilage  cells;  b,  group  of  ° 

four  cartilage  cells;  ct  cell  body  of  car-  Under     pressure,     IS      the 

tilage   cell;    m,   intercellular   substance  cartilage  tisSUC,  which  is 
(cartilage) ;   n,  cell  nucleus  of  cartilage  i          .   , 

^ell  usually  connected  with 

the  bones. 

The  most  remarkable  groups  of  cells  found  in  living 
beings  are  in  the  nervous  tissue,  of  which  the  brain 
and  nerves  are  composed.  These  do  the  thinking 
and  feeling  for  the  body  community. 

Layers  of  curious  cells  cover  the  whole  surface  of 
the  body  and  line  all  its  cavities.  These  are  called 
epithelial  cells,  because  the  skin  or  covering  that 
they  help  to  form  is  called  epithelium. 


«f«l«iMlii^^      •  .-•  , .      :  ••   ,.  ,  •  •-:,:,, 

THIN      SECTION     OF     CARTILAGE,      HIGHLY 
MAGNIFIED. 


THE  LITTLE  WORKERS  OF  THE   BODY 


SECTION  OF  EPITHELIUM  SHOWING  CELLS. 

Among  the  most  wonderful  of  the  many  millions  of 
cells  in  the  body  are  the  gland  cells.  The  glands  are 
groups  of  cells  which  form  some  Gland 
peculiar  substance  for  the  carrying  ceUs> 
on  of  the  work  of  the  body.  There  are  many 
different  kinds  of  gland  cells.  Some  sets  of 
these  cells  form  saliva  ;  others  make  gastric 
juice ;  others  are  found  in  the  liver  making 
bile.  Millions  of  little  groups  of  cells  found 
in  the  skin  make  sweat ;  others  make  fat, 
which  oils  the  hair  and  the  skin.  Other 
gland  cells  separate  from  the  blood  poison- 
ous substances  which  are  formed  in  the 
body  or  which  are  taken  in  with  the  food 
or  drink. 

In  studying  these  cells  and  their  work, 
one  is  constantly  led  to  marvel  at  their  in- 
telligence, faithfulness,  industry,  and  per- 
severance. In  the  action  of  a  gland  cell 
or  tissue-building  cell  we  see  creative  power  mani- 
fested. The  same  creative  power  is  required  to  enable 


EPITHELIAL 
CELLS. 


10 


THE   BODY  IN   HEALTH 


a  cell  to  build  the  minutest  thread  of  fibrous  tissue  as 
was  required  to  make  the  first  man. 

The  one-celled  animal,  living  alone,  must  do  every- 
thing for  itself.  All  that  is  necessary  for  its  life  must 
be  performed  by  that  single  cell.  It  moves  itself 
about,  gathers  its  own  food,  eats  and  digests  it,  and 
discharges  its  wastes.  In  the  community  of  cells 
that  form  the  living  body,  however,  the  work  is  divided 
up.  The  cells  doing  the  same  kind  of  special  work  for 


GLAND  CELLS. 
a,  after  rest ;  b,  after  slight  activity ;  c,  after  greater  activity. 

the  body  are  grouped  together,  and  these  cell  groups 
are  called  organs. 

All  many-celled  animals  and  plants  have  the  work 
divided  up  among  the  different  organs,  and  so  are  said 
Ceil  groups  to  be  organized  and  are  sometimes  spoken  of 
called  as  organisms.  They  are  said  to  belong  to  the 
organic  world.  A  rock  or  a  mountain,  which 
has  no  organs,  is  said  to  belong  to  the  inorganic  world. 

As  the  wood,  brick,  stone,  and  mortar  are  combined 
arid  arranged  to  form  the  parts  of  a  house  and  its  furni- 
ture, so  the  simple  structures  or  tissues  are  combined 


. 
THE  LITTLE  WORKERS  OF  THE   BODY     u 

and  arranged  to  form  the  different  organs  of  the  body. 
In  the  hand,  for  example,  we  have  bone,  muscular, 
connective,  and  skin  tissue  combined  in  such  a  way  as 
to  form  an  organ  suitable  for  grasping.  Some  organs, 
like  the  heart,  are  made  chiefly  of  one  kind  of  tissue. 

Each  organ  has  its  special  work  to  do  for  the  body, 
and  the  life  and  health  of  all  the  cells  depend  upon  its 
work's  being  well  done.  The  stomach  is  an  organ 
for  digesting  the  food,  and  if  it  should  fail  in  this  work, 
all  the  body  cells  would  starve.  The  lungs  take  in  the 
oxygen  that  the  cells  need,  and  the  kidneys  remove 
poisonous  and  waste  matters.  The  heart  pumps  the 
blood  which  carries  the  food  supply  to  every  part  of 
the  body,  so  that  all  the  cells  are  supplied  with  nourish- 
ment. The  brain  and  spinal  cord  send  out  tiny  living 
threads,  called  nerves,  which  run  throughout  the  body, 
dividing  and  subdividing  until  they  reach  every  portion, 
bringing  under  their  influence  each  individual  cell,  with 
the  exception  of  the  floating  cells  in  the  blood. 

When  all  the  cells  and  organs  of  the  body  are  acting 
properly,  a  person  is  said  to  be  in  a  state  of  health. 
When  anything  interferes  with  the  work  of  Ceiisand 
any  of  the  organs  so  that  it  is  done  imper-  organs  in 
fectly  or  not  at  all,   the  person   suffers  dis-  health- 
comfort  and  is  said  to  be  in  a  state  of  ill-health  or 
disease.     It  is  of  the  utmost  importance  that  the  vast 
army  of  little  workers  of  which  we  are  formed  should 
be  kept  in  health  and  vigor.     Anything  which  injures 
them  or  hinders  their  activity  is  dangerous  to  our  life 


12 


THE   BODY  IN  HEALTH 


and  health.  There  are  some  things  which  have  a 
very  injurious  effect  upon  the  bodily  organs ;  among 
these  are  tobacco  and  alcohol. 

By  numerous  experiments  upon  animals,  and  by 
examinations  made  after  death  of  persons  who  had 
used  alcoholic  drinks,  it  has  been  found  that  every 


!\ 


HERE  YOU  SEE  YOUNG  MEN  IN  A  STATE  OF  HEALTH. 

tissue  of  the  body,  especially  the  liver  and  the  brain, 
is  injured  by  alcohol.  Alcohol  lessens  the  activity  of 
the  cells  that  build  the  body  and,  taken  in  strong 
doses,  may  even  paralyze  them  completely.  This  is 
one  reason  why  a  person  who  takes  alcoholic  drinks 
does  not  recover  from  an  accident  so  quickly  as  one 
who  does  not  use  alcohol.  The  cells  are  hindered 


THE  LITTLE  WORKERS  OF  THE   BODY     13 

in  their  work  of  repairing  the  damage  that  has  been 
done.  Many  eminent  surgeons  have  noticed  this 
fact. 

Tobacco  has  the  same  effect  as.  alcohol  upon  the 
tissue-building  cells.  This  is  the  reason  why  the 
boy  who  begins  to  smoke  at  an  early  age  is  puny  and 
stunted  in  his  growth  and  not  properly  developed. 
All  physicians  will  tell  you  that  the  use  of  tobacco  by 
young  persons  is  a  most  injurious  habit. 

HEALTH  PROBLEMS 

1.  Find  out  the  meaning  of  cell.     Do  you  think  the  term  cell 
is  a  good  one  for  the  very  small  parts  of  the  human  body  of  which 
all  organs  are  composed  ? 

2.  Suppose  you  were  talking  with  a  person  who  thought  that 
stones  were  made  up  of  cells.     What  should  you  say  to  him  to  make 
it  clear  to  him  that  cells  are  found  only  in  living  things  ? 

3.  Mention   several   communities  or  colonies   of  cells   in   the 
human  body.     What  are  these  communities  or  colonies  called  ? 

4.  Do  you  know  any  animal  besides  the  amoeba  that  becomes 
two  simply  by  division  ? 

5.  Have  you  ever  seen  a  tree  grafted  ?     How  was  the  work 
done  ?     Did  the  graft  live  ?     If  so,  explain  how  this  was  possible. 

6.  What  does  it  mean  to  say  that  the  body  is  a  community  ? 
Show  in  what  way  it  resembles  a  community  like  the  one  in  which 
you  live,  in  number  and  in  kinds  of  workers. 

7.  Look  up  the  meaning  of  tissue.     Is  it  proper  to  call  some  of 
the  organs  of  the  body  tissues  ?     Why  ? 

8.  Show  in  your  body  an  instance  of  white  fibrous  tissue; 
connective  tissue;    adipose  tissue;    osseous  tissue;    cartilage  tis- 
sue ;  muscular  tissue ;  nervous  tissue. 

9.  Suppose  some  one  organ  of  the  body  did  not  do  its  duty, 


i4  THE   BODY  IN  HEALTH 

What  would  happen  in  the  body  ?     Is  it  the  same  way  in  the  com- 
munity in  which  you  live,  if  some  person  does  not  do  his  duty  ? 

10.    What  does  it  mean  to  be  in  a  state  of  health  ?     What  is  the 
opposite  of  a  state  of  health  ? 

REVIEW  QUESTIONS 

1.  Why  can  we  not  see  the  cells  of  the  human  body  with  the 
eye  alone  ? 

2.  Suppose  you  should  examine  a  piece  of  flesh  under  a  micro- 
scope.    What  should  you  see  ? 

3.  How  can  one  get  specimens  of  the  amoeba  for  study  ? 

4.  Describe  the  amoeba  seen  under  the  microscope. 

5.  How  are  the  cells  of  the  body  formed  ? 

6.  What  is  the  nucleus  of  the  cell  ?     What  happens  to  it  when 
any  cell  is  about  to  become  two  cells?     Of  what  are  the  bodies  of 
large  animals  made  ?     With  what  does  the  body  of  every  animal 
begin  ? 

7.  What  does  it  mean  to  say  there  is  "division  of  labor"  in 
the  human  body  ? 

8.  How  are  the  tissues  of  the  body  made  up  ? 

9.  Mention  the  various  kinds  of  tissues  and  their  uses. 

10.  What  are  the  epithelial  cells  ?     Where  are  they  found  ? 

11.  What  are  the  gland  cells  and  what  are  their  uses  ? 

12.  What  is  the  meaning  of  organs?     Mention  a  number  of 
organs  in  the  human  body. 

13.  Mention  the  tissues  which  compose  the  hand. 

14.  What  is  necessary  to  keep  the  body  in  a  state  of  health  ? 

15.  What  has  been  found  regarding  the  influence  of  alcohol 
upon  the  workers  of  the  body  ?     What  organs  are  hurt  the  most 
by  alcohol  ? 

1 6.  What  is  the  effect  of  tobacco  upon  the  workers  of  the 
body  ? 


CHAPTER   II 

THE  MAINTENANCE  OF  THE  BODY 

No  large  community  of  people  remains  exactly  the 
same  for  any  length  of  time.  Constant  changes  take 
place  in  it.  Daily  some  of  its  members  are  dying  or 
leaving,  new  ones  are  being  born,  and  others  are 
coming  in  from  other  places.  When  the  number 
added  is  greater  than  the  number  lost,  the  community 
grows  in  size,  of  course.  Do  you  know  that  this  is 
true  also  of  the  communities  or  colonies  of  cells  that 
compose  the  living  body  ?  Many  millions  of  the  cells 
die  in  the  course  of  a  single  day.  Eight  million  blood 
cells  are  dying  every  second  of  our  lives.  If  no  new 
ones  were  supplied  to  take  their  places,  what  would 
happen  to  the  body  ?  Besides  the  cells  needed  to 
take  the  place  of  those  that  have  died,  the  child  or 
the  young  animal  needs  an  increase  of  cells  to  provide 
for  its  growth.  Why  ? 

All   living  things   grow.     This   is   one  of  the   chief 
differences    between    the    organic    and    the    inorganic 
world.     A  lifeless  object,  such  as  a  rock  or  HOW  we 
mountain,   does  not  grow,   although  it  may  ST°W- 
increase  in  size  by  the  simple  addition    of  material. 
Living  things,   plants   and   animals,   grow   by    taking 

15 


16  THE   BODY  IN  HEALTH 

material  into  themselves  and  changing  it  into  their 
own  substance.  The.  growth  of  a  human  being,  from 
the  very  beginning  until  he  reaches  the  full  stature  of 
a  perfect  man,  takes  place  only  through  the  making 
over  of  the  food  he  eats. 

All  the  cells  of  the  body,  which  are  living  and  active, 
need  food  to  maintain  their  life  and  supply  them  with 
energy  for  their  work.  Hunger  is  the  appeal  of  the 
cells  for  more  food. 

The  living  body  is  both  like  a  house  and  like  a 
machine.  A  machine  wears  out  much  more  quickly 
than  a  building,  for  the  reason  that  it  works.  The 
work  performed  in  and  by  the  body  wears  it  out  so 
that  it  is  in  constant  need  of  repairs.  The  wearing 
out  process  is  so  great  that  the  entire  body  is  rebuilt 
many  times  during  a  long  life.  How  is  the  material 
for  the  necessary  repairs  supplied  ? 

The  living  human  body  is  always  warm.  In  summer 
or  winter,  no  matter  what  the  temperature  of  the 
surrounding  air  may  be,  the  body  temperature  is  always 
maintained  at  nearly  100°.  In  Health  Habits  you  have 
learned  something  about  the  combustion,  or  slow  burn- 
ing, by  which  the  body  heat  is  kept  up.  To  produce 
heat,  something  must  be  consumed.  The  life  fire 
that  warms  the  body  consumes  it  just  as  burning 
consumes  a  candle  or  as  fuel  is  consumed  in  the  stove. 
Of  course,  a  constant  supply  of  fuel  is  needed  to  keep 
this  life  fire  steadily  burning.  How  is  this  supply 
furnished  ? 


THE   MAINTENANCE  OF  THE   BODY         17 

What  is  ordinarily  spoken  of  as  fire  is  an  active 
burning,  accompanied  by  a  flame.  When  combustion 
is  less  active,  the  heat  is  less  intense,  and  there  may  be 
no  visible  flame.  It  is  by  this  latter  sort  of  combustion 
that  a  dead  tree,  lying  upon  the  ground  in  the  woods, 
is  gradually  consumed.  In  time  it  will  disappear  as 
completely  as  though  it  had  been  burned  up  in  the 
stove.  The  amount  of  heat  produced  by  the  burning 
of  a  tree  is  just  the  same,  whether  it  rots  in  the  forest 
or  is  burned  in  a  furnace ;  but  in  the  furnace  the  heat 
is  given  off  in  a  much  shorter  time.  The  amount  of 
heat  produced  by  the  body  every  hour  has  been  es- 
timated to  be  sufficient  to  raise  two  and  a  half  pints 
of  water  from  freezing  to  the  boiling  point,  or  to  boil 
seven  gallons  of  ice  water  every  twenty-four  hours. 

Another  important  source  of  bodily  waste  is  work. 
Work,  like  heat,  requires  the  consuming  of  something. 
The  locomotive  can  not  pull  its  train  of  cars  How  the 
without  using  coal.     You  know,   I   suppose,  ceils  get 
the  amount  of  fuel  consumed  by  a  locomotive  ****** 
is  in  proportion  to  the  amount  of  work  it  does. 
So  the  locomotive  which  pulls  the  largest  train  con- 
sumes the  most  coal.     Just  as  the  locomotive  gets  its 
power  to  work  from  the  fuel  that  is  burned  under  its 
boiler,  so  the  cells  in  the  body  get  their  power  to  work 
from  the  food  that  is  used  in  it.     All  the  work  done 
in  and  by  the  body  consumes  materials  that  must  be 
made  good  by  the  food  supply.     The  body,  therefore, 
has    only    one   source   of  energy.     That   is  food.     The 


i8 


THE   BODY  IN   HEALTH 


greater  the  amount  of  work  done,  the  greater  the 
amount  of  food  needed.  Think  for  a  moment  of  the 
tremendous  amount  of  work  done  daily  by  the  cells 
of  the  body.  It  has  been  carefully  estimated  that 
the  work  which  the  body  is  capable  of  doing  daily  is 
equal  to  the  lifting  of  900  tons  one  foot  high.  More 


9OO 

TON6 


THE    BODY    IS    CAPABLE    OF    DOING    AN    AMOUNT    OF    WORK    EACH    DAY    EQUAL    TO 
LIFTING  900  TONS   ONE    FOOT   HIGH. 

than  one  seventh  of  this  work  is  done  by  the  heart, 
which  is  constantly  at  work,  without  a  moment's 
rest  day  or  night,  pumping  the  blood  to  every  part 
of  the  body.  The  work  of  the  lungs  and  of  the  muscles 


THE   MAINTENANCE  OF  THE   BODY         19 

that  move  the  breathing  apparatus  also  goes  on  every 
moment  during  life.  The  balance  of  the  work  is  done 
by  the  muscles  of  the  limbs  and  the  trunk.  To  per- 
form in  ten  hours  with  the  muscles  all  the  work  done 
daily  by  the  body,  a  man  would  have  to  lift  his  own 
weight  a  foot  high  every  three  seconds. 

We  see  then  that  there  are  two  things  that  the  food 
supplies  to  the  body :  material  for  the  building  of 
body  tissue, --bone,  muscle,  blood,  brain,  and  all 
the  organs  of  the  body ;  and  energy,  which  is  used 
in  the  body  in  many  different  ways,  --  producing  heat, 
doing  muscular  and  mental  work,  keeping  the  heart 
beating,  and  enabling  all  the  different  organs  and 
glands  of  the  body  to  perform  their  work. 

An  examination  of  human  dust  shows  us  the  materials 
of  which  the  body  is  composed.  The  following  table 
shows  the  different  substances,  and  the  amounts  of 
each,  in  the  body  of  a  person  weighing  150  pounds. 
You  need  not  try  to  remember  these  different  things 
now;  only  look  them  over  to  get  an  impression  of 
what  the  body  is  made. 

ELEMENTS 

Oxygen .     .     .  97.5  Pounds 

Carbon .     .     .    >     .  27.0  " 

Hydrogen 15.0  " 

Nitrogen 4.5  " 

Calcium 3.0  " 

Phosphorus 1.5  " 

Potassium „  .5  " 


20 


THE   BODY  IN  HEALTH 


ELEMENTS 

Sulphur  . 
Chlorine  . 
Sodium  . 
Magnesium 
Iron  .  . 
Fluorine  . 
Sili 


.4  Pound 

.2 
.2 

1.2  Ounces 
.1 

Traces 


icon 


Let  us  now  see  where  we  get  the  material  that  forms 
our  bodies.     Where  does  it  come  from  ?     Every  par- 
ticle of  it  comes  from  the  earth,  the  air,  and 
Where  the  ^Q  water      f  ne  human  body,  however,  does 

material  in  J  '     . 

the  body  not  have  the  power  to  make  living  substance 
comes  out  of  earth  and  air.  Animals  can  use  as 
food  only  substances  that  have  been  pre- 
pared for  them  by  plants.  Here,  for  instance,  are  a 
piece  of  bread  and  a  piece  of  coal.  Both  contain 

material  and  energy,  and 
some  of  the  same  ele- 
ments. Yet  one  is  a 
food,  and  the  other  is 
not  a  food.  The  coal 
may  be  burned  in  a 
locomotive  to  furnish 
both  heat  and  energy, 
but  it  can  not  be  so  used 
in  the  human  body. 

You  must  see  that  the  material  coming  from  the 
earth,  the  air,  and  the  water  must  first  pass  through 


WHY  CAN  NOT  THE  COAL  BE  BURNED  IN 
THE  BODY  ? 


f  f 

THE  MAINTENANCE  OF  THE   BODY        21 

the  plant,  before  it  can  be  used  by  animals  as  food. 
The  plant  is  the  workshop  or  factory  where  the  food 
for  animals  is  produced.  A  plant,  to  illustrate,  takes 
from  the  air  carbonic  acid  gas,  about  which  you  have 
already  learned.  This  is  not  a  food.  From  the  soil 
the  plant  takes  up  water,  which  is  not  a  food.  Out 
of  these  two  combined  it  makes  starch,  which  is  a 
food.  Sunlight,  the  great  source  of  energy,  can  not 
be  absorbed  directly  and  used  by  the  body.  The 
energy  you  use  to-day  in  doing  your  daily  work  was 
at  one  time  in  the  form  of  sunbeams,  which  were  picked 
up  by  a  plant,  changed  into  chemical  compounds,  and 
stored  up.  Every  vegetable  product,  as  wheat,  corn, 
potato,  is  such  a  storehouse.  Every  fruit,  every  seed, 
every  nut,  is  a  little  bundle  of  concentrated  light, 
stored  until  it  is  needed  for  the  growth  and  develop- 
ment of  a  new  plant  or  to  furnish  heat  and  energy  to 
some  member  of  the  animal  kingdom. 

This  calls  our  attention  to  an  important  difference 
between  plants  and  animals.     A  plant  is  a  food  pro- 
ducer, a  storehouse  of  energy.     An  animal  is  a  pi^g  the 
food  consumer,  an  expender  of  energy.     Ani-  only  food 
mals,  although  they  are  sometimes  used  for  Producers- 
food,   do  not   make  foods.     A  plant   is  the  only  real 
food  factory ;  the  only  place  in  the  world  where  a  food 
is  actually  produced.     A  lion,  in  dining  upon  an  ante- 
lope, is  only  eating  at  second-hand  the  grass  and  herbs 
which  the  antelope  has  eaten.     A  man,  in  eating  roast 
beef,  is  taking  at  second-hand  the  corn  upon   which 


22  THE   BODY  IN   HEALTH 

the  ox  was  fed.  If  animals  were  to  feed  upon  each 
other  only,  the  animal  kingdom  would  soon  disappear 
from  the  face  of  the  earth.  Animals  eat  the  foods 
produced  by  plants.  Without  plants  animals  could 
not  live. 

We  must  now  study  the  substances  that  are  adapted 
to  serve  as  food  for  man.  A  substance  which  can  be 
Composi-  used  by  the  body  to  furnish  it  with  material 
tionof  for  building  or  repairs  or  with  energy  for 
heat  and  work  is  called  a  nutrient.  We 
have  seen  that  one  purpose  of  food  is  to  supply  the 
body  with  warmth  and  power  to  work.  These  special 
needs  are  met  by  two  classes  of  nutrients,  carbohydrates 
(starch,  dextrine,  and  sugar)  and  fats.  The  building 
material  for  the  body  is  furnished  by  another  class  of 
nutrients  called  proteins.  These  —  carbohydrates, 
fats,  and  proteins  —  are  the  three  great  classes  of 
nutrients. 

In  addition  there  are  :  - 

Salts,  which  are  essential  not  only  for  the  bones,  but 
for  all  living  tissues  of  the  body.  (By  salts  we  do  not 
mean  "table  salt,"  but  organic  combinations  of  lime, 
magnesia,  phosphorus,  potash,  and  other  elements) ; 

Flavoring  Substances,  which  render  the  food  agreeable 
to  the  taste ; 

Cellulose,  an  indigestible  substance  found  in  all  vege- 
table foods,  which  is  highly  essential  to  give  bulk  to 
the  food  mass  and  stimulate  the  activity  of  the  stomach 
and  intestines. 


, 

THE   MAINTENANCE  OF  THE   BODY         23 

Vitamines,  subtle  substances  which  are  found  in 
fresh,  uncooked  foods  and  which  are  absolutely  nec- 
essary for  the  complete  nourishment  of  the  body. 
These  substances  are  so  refined  and  so  active  that  little 
more  is  known  about  them  except  the  fact  that  they 
exist  and  that  they  are  likely  to  be  destroyed  by  cook- 
ing. Sailors  get  scurvy  by  the  exclusive  use  of  cooked 
food. 

We  have  already  learned  that  starch  is  made  by  the 
plant  out  of  carbonic  acid  gas,  which  it  gets  from  the 
air,  and  water,  which  it  gets  from  the  earth.  Starch 
is  the  most  abundant  of  the  nutrients.  It  is  found  in 
all. grains  and  vegetables,  and  in  green  fruits,  though 
not  in  ripe  fruits. 

Starch  consists  of  little  granules,  each  one  of  which 
is  inclosed  in  a  tiny  envelope  made  of  a  woody  sub- 
stance, called  cellulose.  For  this  reason,  raw  starch 
can  not  be  digested  well  by  a  human  being.  The 
process  of  cooking  breaks  up  the  envelope  and  releases 
the  starch,  which  can  then  be  reached  and  acted  upon 
by  the  digestive  fluids  in  the  body.  The  picture  shows 
different  forms  of  starch  granules  found  in  the  common 
grains  and  vegetables. 

Sugar,  although  very  unlike  starch  in  looks  and 
taste,  is  almost  like  it  in  composition.  When  starch 
is  digested,  it  is  made  into  sugar.  Sugar  is  found 
in  all  fruits  and  in  some  vegetables,  such  as  corn, 
beets,  and  sweet  potatoes.  There  are  different 
kinds  of  sugars.  The  sugar  of  fruits  is  called  fruit 


24  THE   BODY  IN  HEALTH 

sugar.     A  sweet  substance  found  in  milk  is  known  as 
milk  sugar.     A  peculiar  sugar  produced  in  the  sprout- 


STARCH   CELLS   OF  POTATO. 

a,  cells  of  raw  potato;  b,  cells  of  partially  cooked  potato;   c,  cells  of  thoroughly 

boiled  potato. 

ing  or  malting  or  grain  is  called  malt  sugar  or  maltose. 
Sugar  furnished  by  the  sugar  cane,  the  beet  root,  or 
the  sap  of  the  maple  tree  is  known  as  cane  sugar. 

Fats  are  found  in  both  animal  and  vegetable  foods. 
Butter,  lard,  and  suet  are  the  principal  forms  of  animal 
fats  used  as  foods.  Vegetable  oils  come  chiefly  from 
nuts,  from  various  seeds  such  as  the  cotton  seed,  and 
from  oily  fruits  such  as  the  olive. 

Proteins  contain  the  carbon,  hydrogen,  and  oxygen 
found  in  fats,  starch,  and  sugar,  and  in  addition  to  these 
they  also  contain  nitrogen,  and  for  this  reason  they 
are  sometimes  called  nitrogenous  foods.  .  Proteins 
are  abundant  in  animal  foods, --lean  meat,  milk, 
cheese,  and  eggs.  Of  the  foods  obtained  from  plants, 
proteins  are  found  chiefly  in  nuts,  peas,  beans,  and 
lentils,  though  they  are  contained  also  in  all  grains 
and  in  very  small  quantities  in  most  vegetables. 


THE   MAINTENANCE  OF  THE   BODY         25 

LIST  OF  COMMON  FOODS  RICH  IN  PROTEINS,  FATS,  AND  CAR- 
BOHYDRATES 


PROTEINS 


FATS 


CARBOHYDRATES 


{Animal} 


Milk 
Cheese 


eat 


(Vegetable) 

Legumes  (dried  peas, 

beans,  lentils) 
Nuts 
Oatmeal 
Wheat 


(Animal) 

Milk 

Cream 

Butter 

Egg  yolk 

Suet 

Lard 

Fat  meat 

(Vegetable) 

Nuts 

Cocoanut  oil 

Olive  oil 

Other  vegetable  oils 


(Vegetable) 

All  cereals,  All 
foods  made  from 
cereals,   Starchy 
vegetables,  par- 
ticularly the  Irish 
potato,  Sweet 
potato,   Dasheen, 
Green  corn,  Green 
peas,   Sweet  fruits, 
Figs,   Banana, 
Apple,   Prune, 
Pear,   Raisin, 
Sugars,   Legumes, 
Chestnuts,  and 
some  other  nuts 


The  carbohydrates  and  fats,  which  are  composed  of 
the  same  elements  (carbon,  hydrogen,  oxygen),  serve 
the  same  purpose  in  the  body.  They  are  the  fuel 


26 


THE   BODY  IN   HEALTH 


or  energy-giving  foods,  which  are  burned  up  in  the 
body  to  furnish  it  with  warmth  and  power  to  work. 
Uses  of  When  not  needed  for  immediate  use,  they 
the  dif-  may  be  stored  up  in  the  tissues  of  the  body, 
ferent  just  as  coai  js  stored  up  in  the  tender  of  a 

locomotive,  to  be  used  as  needed. 
The  proteins  are  a  most  important  class  of  nutrients 
because  they  furnish  the  building  material  for  the 
body.  Just  as  the  carbohydrates  and 
fats  correspond  to  the  coal  burned  in 
the  locomotive,  the  proteins  correspond 
to  the  iron,  brass,  and  other  materials 
out  of  which  the  locomotive  is  made. 
Nitrogen,  which  is  contained  only  in 
protein,  is  the  element  needed  for  cell 
building,  and  it  is  this  that  gives  the 
protein  foods  their  great  importance. 
A  growing  child,  whose  body  is  in  pro- 
cess of  building,  needs  these  nitrogenous 
foods  in  larger  quantities  than  a  person 
who  is  full-grown  and  needs  only  the 

OATS,  CORN,  WHEAT,  .     !  r  .  ry^i 

AND  RICE  MAKE  material  ^  necessary  for  repairs.  The 
EXCELLENT  FOODS  foods  which  nature  has  provided  for  the 
WHEN  PROPERLY  ust  Qf  tke  yOung  animal  are  rich  in 

PREPARED.  WHY  r  J          ° 

proteins.  The  white  or  albumen  of  the 
egg,  out  of  which  the  young  chick  is  to  be  con- 
structed, is  composed  wholly  of  this  element.  Milk, 
also,  which  is  the  natural  food  for  young  animals, 
contains  an  abundance  of  protein. 


THE   MAINTENANCE  OF  THE   BODY        27 

Proteins  may  be  burned  in  the  body  to  furnish 
energy,  but  their  chief  use  is  for  building  material. 
There  is  no  provision  in  the  body  for  the  storing  up 
of  the  proteins,  or  building  foods,  as  there  is  for  the 
storage  of  the  fuel  foods,  hence  it  is  important  to  take 
just  the  proper  amount  each  day. 

Certain  minerals  are  needed  in  small  amounts.  Of 
these  common  salt  is  the  one  most  familiar  to  us.  This 
is  found  in  sufficient  quantities  in  most  of  our  foods,  but 
we  often  add  more  in  cooking  and  eating, — often  too 
much.  Lime,  which  is  used  in  making  bones  and  is  es- 
pecially needed  by  a  growing  child  for  the  building  up  of 
his  body,  is  found  in  milk  and  grains  and  eggs.  A  small 
amount  of  iron  is  needed  for  the  formation  of  the  red 
blood  cells. 
This  is  found 
in  some  fruits, 
especially  in 
the  straw- 
berry and  the 
apple,  in  the 
yolk  of  egg, 
and  in  the 
green  parts  of 
veg  e  t  ables. 

r>  r      j  FRUITS  CONTAIN  MINERALS  AND  MUCH  WATER. 

Raw       foods, 

such  as  celery  and  lettuce,  are  valuable  for  the  min- 
erals which  they  furnish. 

Another  substance  very  necessary  to    the  body  is 


28 


THE   BODY   IN  HEALTH 


water,  which  as  you  know  comprises  a  large  part  of 
the  body.  Water  is  lost  from  the  body  chiefly  in  the 
removal  of  wastes.  But  besides  that  which  is  carried 
off  through  the  bowels  and  kidneys,  water  is  also  con- 
stantly passing  off  through  the  lungs  and  skin,  in  the 
form  of  an  invisible  vapor.  The  moisture  of  the  breath 
can  be  seen  when  one  is  in  the  open  air  on  a  frosty  morn- 
ing. When  one  exercises  violently,  or  is  exposed  to  great 
heat,  the  water  thrown  off  by  the  skin  becomes  visible 
in  the  form  of  perspiration.  The  amount  of  water  lost 
daily  is  three  or  four  pints,  and  this  loss  must  be  made 
good  by  drinking  or  getting  water  in  our  food.  Be- 
sides the  water  that  we  drink,  we  get  a  considerable 
amount  in  our  foods.  Even  what  are  called  dry 
foods,  such  as  rice  and  beans,  contain  some  water,  and 
other  foods  are  largely  composed  of  it.  Potatoes,  for 

instance,  are  more  than 
eighty  per  cent  water. 
At  the  end  of  the  book 
you  will  find  an  appen- 
dix giving  the  composi- 
tion of  all  the  ordinaty 
foods,  and  you  should 
examine  this  and  tell 
what  nutrient  is  most 
prominent  in  the  foods 
you  eat  most  freely. 
Another  substance  that  is  absolutely  necessary  to 
the  life  and  work  of  the  cells  is  oxygen,  which  we  get 


ARE    THESE     GOOD     FOODS  ?       WHAT    DOES 
EACH    CONTAIN    IN    LARGEST   MEASURE  ? 


[?  I. 

THE  MAINTENANCE  OF  THE   BODY        29 

from  the  air.  If  the  supply  of  oxygen  is  cut  off  from 
the  body  for  only  a  few  moments,  the  life  fire  dies  out. 
How  the  necessary  oxygen  is  supplied  to  the  cells 
and  what  use  is  made  of  it  will  be  told  in  another 
chapter. 

A  poison  is  just  the  opposite  of  a  food.      Instead  of 
furnishing  the   body  with   nourishment,    it   interferes 
with  the  life  and  work  of  the  cells,  disturbing  Poisons 
them  in  such  a  way  as  to  cause  sickness  and  the  op- ' 
death.     A  true  food  must  not  contain  any  P°siteof 
substance  that  is  in  any  way  harmful  to  the 
body. 

There  has  been  in  recent  years  much  discussion  as 
to  whether  or  not  alcohol  is  a  food.  Alcohol,  as  we 
have  already  learned,  paralyzes  the  cells  that  make 
bone  and  flesh.  All  the  delicate  organs  by  which  the 
life  work  of  the  body  is  carried  on  are  injured  by  it 
and  hindered  in  their  work.  Not  only  are  the  organs 
injured  and  weakened  by  it,  but  the  task  of  removing 
this  injurious  thing  (for  it  is  injurious)  from  the  body 
adds  greatly  to  their  work. 

No  food  prepared  for  us  by  Nature  is  composed 
solely  of  one  of  the  nutrients  that  we  have  been  study- 
ing. They  are  combined  in  the  foods  in  the  way  in 
which  they  will  best  meet  the  needs  of  the  body.  We 
may  dine  with  a  king  and  have  a  very  elaborate  menu 
with  the  food  prepared  in  many  different  ways,  but  we 
can  not  have  in  it  more  than  these  few  simple  nutrients 
that  we  have  studied.  On  the  other  hand,  we  may  eat 


30  THE   BODY   IN   HEALTH 

our  meal  by  the  roadside  with  a  laboring  man,  and  if 
he  has  in  that  meal  all  of  these  nutrients  in  the  right 
proportions,  our  body  will  be  furnished  with  nourish- 
ment just  as  well  as  though  we  had  eaten  with  the  king. 

HEALTH  PROBLEMS 

1.  What  changes  are  taking  place  in  the  community  in  which 
you  live  ?     Is  the  community  growing?     How  can  you  tell  ? 

2.  Have  you  noticed  how'  very  hungry  growing  puppies  and 
kittens  are  all  the  time  ?     Explain.     Is  this  true  of  all  growing 
animals  ?     Why  ? 

3.  Suppose  one  could  eat  no  food,  what  would  happen  to  him  ? 
Why  ?•    Would  it  happen  more  quickly  if  he  had  to  work  hard  than 
if  he  were  idle  ?     Why  ? 

4.  Have  you  ever  had  a  physician  "take  your  temperature"? 
If  so,  why  did  he  do  it? 

5.  When  one  goes  out  into  zero  weather,  how  is  his  heat  kept 
up  to  about  100°  ?     What  would  happen  if  it  should  drop  a  few 
degrees  ? 

6.  Think  of  some  way  to  prove  that  the  cells  feed  on  the  food 
taken  into  the  body. 

7.  Are  you  more  hungry  when  you  work  or  play  hard,  or  when 
you  are  out  in  the  cold  much,  than  when  you  live  in  a  warm  house 
all  the  time  and  do  no  work  ?     Explain. 

8.  It  is  said  that  an  apple,  or  a  kernel  of  corn,  or  a  nut  is  a 
sort  of  storehouse  of  light.     From  where  does  the  light  come  ? 

9.  Imagine  that  you  are  talking  to  a  person  who  does  not  see 
that  plants  take  materials  from  the  air  and  the  earth  and   make 
them  into  food.     How  could  you  make  it  so  clear  that  he  could 
not  help  but  see  it  ? 

10.  In  what  way,  or  by  means  of  what  organs,  does  the  plant 
get  its  materials  from  the  air  ?     From  the  earth  ? 


THE   MAINTENANCE  OF  THE   BODY        31 

11.  Make  a  list  of  common  articles  of  food  which    contain 
starch,  protein,  fats,  sugar. 

12.  Bring  to  the  class  small  samples  of  the  different  kinds  of 
sugar. 

13.  Can  you  tell  starchy  foods,  fats,  foods  rich  in  sugar,  and 
those  rich  in  protein  by  the  sense  of  taste  alone  ?     Explain. 

14.  Should  a  growing  boy  eat  more  of  eggs,  peas,  beans,  cheese, 
and  the  like  than  a  full-grown  man  who  is  doing  very  little  muscular 
work?     Why? 

15.  Show  by  an  experiment  that  a  potato,  or  an  apple,  or  a 
cucumber  is  largely  water. 

REVIEW  QUESTIONS 

1.  What  is  necessary  that  a  living  thing,  plant  or  animal,  may 
grow  ? 

2.  What  do  living  cells  need  in  order  to  maintain  their  life  ? 

3 .  Why  is  the  living  body  both  like  a  house  and  like  a  machine  ? 

4.  What  is  the  meaning  of  the  "vital  fire"  ? 

5.  What  is  the  normal  temperature  of  the  body  ? 

6.  How  is  heat  produced  in  the  body  ? 

7.  What  is  the  difference  between  the  burning  of  fuel  in  the 
human  body  and  the  burning  of  fuel  in  a  stove  ? 

8.  How  do  the  cells  get  the  energy  for  their  work  ? 

9.  What  happens  in  the  body  when  work  is  done  ?     Show  that 
the  body  at  work  is  something  like  a  locomotive  pulling  cars. 

10.   What  organs  of  the  body  are  constantly  at  work  ? 
n.   What  two  things  does  food  supply  to  the  body  ? 

12.  What  must  happen  to  the  material  coming  from  the  earth, 
the  air,  and  the  water  before  it  can  be  used  by  animals  as  food  ? 
How  does  a  plant  make  starch,  for  instance  ? 

13.  What  is  the  difference  between  a  piece  of  bread  and  a  piece 
of  coal  so  far  as  the  body  is  concerned  ? 

14.  What  is  a  nutrient  ?     Name  a  number  of  nutrients. 


32  THE   BODY  IN   HEALTH 

15.  Which  nutrient  supplies  the  building  material  for  the  body  r 
Which  warmth  and  power  to  work  ?  Which  the  material  for  making 
bones,  teeth,  and  such  parts  of  the  body  ? 

1 6.  Which  is  the  most  abundant  of  the  nutrients  ? 

17.  Where  is  starch  found  abundantly?     Discuss  starch  as  a 
food. 

1 8.  In  what  fruits  and  vegetables  is  sugar  found  ?     Name  the 
kinds. 

19.  In  what  foods  are  the  fats  found  ?    Proteins  ? 

20.  What  are  the  uses  of  carbohydrates  and  fats  in  the  body  ? 
Of  proteins  ? 

21.  Which  of  the  classes  of  nutrients  does  the  growing  animal 
need  especially  ? 

22.  Mention  the  minerals  which  are  needed  in  the  body.     In 
what  foods  are  they  found  ? 

23.  What  is  oxygen  ?     What  happens  to  the  body  if  the  supply 
of  oxygen  is  cut  off  even  for  a  moment  ? 

24.  How  does  a  poison  affect  the  body  ?     Is  alcohol  a  food  or  a 
poison  ? 


CHAPTER  III 
How  FOOD  BECOMES  LIVING  TISSUE 

THE  food  substances  or  nutrients  about  which  you 
have  been  learning  can  not  be  taken  up  just  as  they  are 
used  by  the  cells  as  food.  A  great  deal  of  preparatory 
work  is  necessary.  This  work  of  preparation  is  called 
digestion.  We  have  already  seen  how  the  work  of  the 
body  is  divided  up  among  the  different  groups  of  cells 
that  form  the  organs  of  the  body.  The  groups  whose 
work  it  is  to  prepare  the  food  are  called  the  digestive 
organs. 

If  you  have  ever  visited  a  large  bakery  establish- 
ment, you  have  seen  how  the  work  is  divided  up  among 
the  different  workers.  One  attends  solely  to  the  mixing 
and  kneading  of  the  dough,  which  is  then  passed  to 
another  who  spends  his  time  in  rolling  it  out  to  the 
required  thickness.  Another  worker  then  takes  it  and 
cuts  it  into  pieces  of  the  right  size  and  shape  and 
passes  it  to  yet  another  who  superintends  the  baking. 
In  like  manner  the  food  you  eat  is  passed  from  one  to 
another  of  the  cell  groups  called  the  digestive  organs, 
and  each  group  has  some  special  part  of  the  work  of 
preparation,  that  we  call  digestion,  to  perform. 

D  33 


34 


THE   BODY  IN  HEALTH 


There  is  a  long  tube  in  which  the  work  of  digestion 
takes  place,  and  this  is  called  the  alimentary  canal  or 

The  food        food  tube. 

canal.  Aliment 
means  food,  and  the  ali- 
mentary canal  is  simply 
the  food  channel  in 
the  body.  It  is  from 
twenty-five  to  thirty 
feet  long  and  is  lined 
throughout  with  fine 
pink  skin  called  mucous 
membrane,  which  you 
can  see  in  the  mouth. 
This  is  kept  always 
moist,  so  that  the  food 
may  easily  be  moved 
along  it. 

The  cell  groups  whose 
work  it  is  to  prepare  the 
food  are  stationed  at 
various  places  along  the 
route  that  the  food  must 
travel,  just  where  their 
services  are  needed. 
Each  group  prepares  a 
special  kind  of  fluid  or 
juice  which  it  pours  out  upon  the  food.  These  fluids 
are  called  the  digestive  juices.  There  are  five  digestive 


START  WITH  GATE  i,  AND  SEE  IF  YOU  CAN 

TELL  WHAT  HAPPENS  TO  THE  FOOD  AS  IT 
PASSES  THROUGH  EACH  OF  THE  ORGANS  OF 
DIGESTION. 


HOW  FOOD   BECOMES  LIVING  TISSUE       35 

organs,  and  so  there  are  five  different  kinds  of  digestive 
juice. 

There  are  no  openings  in  the  alimentary  canal, 
except  at  the  entrance  to  the  body  and  the  exit  from 
it.  All  the  food,  therefore,  must  be  soaked  up  Digestive 
or  absorbed  by  the  walls  of  the  canal  in  order  to  Juices- 
pass  through  it  into  the  body  for  the  use  of  the  cells, 
which  can  take  their  food  only  in  a  liquid  form.  Most 
of  our  foods  consist  of  solid  particles  which  do  not 
dissolve  in  water.  Mix  some  sugar  with  a  glass  of 
water,  and  you  will  find  that  after  a  few  minutes  the 
sugar  has  seemingly  completely  disappeared.  It  is 
dissolved  in  the  water,  and  you  can  detect  its  presence 
only  by  the  taste.  If  you  treat  a  piece  of  bread  in 
the  same  way,  you  will  see  that  it  does  not  dissolve 
in  the  water  but  only  mixes  with  it.  If  you  strain 
the  water  containing  the  sugar  through  a  fine  sieve 
or  cloth,  both  sugar  and  water  will  pass  through 
together  and  there  will  be  nothing  left  in  the  cloth. 
But  if  you  strain  in  the  same  way  the  water  with 
which  the  bread  has  been  mixed,  the  water  will  pass 
through  the  cloth  but  most  of  the  bread  will  remain 
behind. 

The  work  of  digestion  is  simply  the  work  of  chang- 
ing the  insoluble  (Look  up  the  meaning  of  insoluble) 
substances  of  the  food  into  substances  that  are  readily 
dissolved  and  so  will  pass  easily  through  the  walls  of 
the  food  tube  into  the  blood. 

At  the  very  entrance  of  the  food  canal  is  a  station 


THE   PERMANENT  TEETH, 
UPPER  JAW. 


36  THE   BODY   IN  HEALTH 

where  the  food  must  tarry  for  a 
The  first  while  and  be  worked  over 
step  in  before  it  starts  on  its 
digestion.  journey  through  the 

body.     This  station  is  the  mouth, 
the  first  of  the  digestive  organs. 
The  work  done  in  the  mouth,  as 
we  learned  in  Health  Habits,  is  of 
the  utmost  importance  because  all 
the  rest  of  the  work  of  digestion 
depends  upon  thorough   prepa- 
ration being  given  to  the  food 
in  the  mouth. 

An  important  part  of  this 
work  is  the  chewing  or  mastica- 
tion of  the  food,  which  is  done 
by  the  teeth.  An  infant  is  born 
without  teeth.  Between  the 
ages  of  seven  months  and  two 
years  the  temporary  or  milk 
teeth,  twenty  in  number,  make 
their  appearance.  By  the  twelfth 
year  these  temporary  teeth  have 
given  place  to  the  permanent 
set.  A  complete  set  of  per- 
manent teeth  in  an  adult  con- 
sists of  thirty-two  teeth.  Each 
jaw  contains  four  front  teeth,  called  incisors  or  cut- 
ting teeth ;  two  cuspids,  one  on  each  side  of  the 


Keck 


SECTION    OF    A    CANINE    OR 

CUSPID    TOOTH. 


i 

HOW   FOOD   BECOMES   LIVING  TISSUE       37 

incisors ;  four  bicuspids,  two  on  each  side ;  and  six 
double  teeth,  three  on  each  side,  called  the  molars  or 
grinding  teeth.  The  purpose  of  the  front  or  single 
teeth  is  to  cut  or  bite  the  food,  and  the  work  of  the 
double  teeth  is  to  crush  or  grind  it  into  a  pulp,  the 

condition  in  which  it -should     

be  before  it  is  swallowed. 

The  teeth  are  helped  in 
the  work  of  mastication  by 
the  tongue,  which  moves 
the  food  about,  passing  it 
from  side  to  side  of  the  mouth 
until  it  is  all  thoroughly 
chewed.  In  the  tongue  also 
are  taste  buds,  of  which  we 
have  learned,  by  which  the 
different  flavors  in  foods  are 
detected. 

The  work  of  mastication  is  also  assisted  by  the  saliva, 
the  first  of  the  digestive  juices  to  be  poured  out  The  work 
upon  the  food.     This  moistens  and  softens  the  of  the 
food,  so  that  it  is  more  easily  made  into  a  saliva' 
creamy  pulp. 

The  saliva  does  much  more  to  the  food  than  merely 
to  moisten  it.  If  you  chew  a  hard  crust  of  bread  for 
a  long  time,  you  will  notice  that  after  a  while  it  be- 
comes quite  sweet  to  the  taste.  This  is  because  some 
of  the  starch  has  actually  been  changed  by  the  saliva 
into  the  kind  of  sugar  called  maltose. 


TASTE  BUDS  IN  THE  TONGUE. 


38  THE   BODY  IN  HEALTH 

The  groups  of  cells  which  form  the  saliva  and  pour 
it  on  to  the  food  are  called  salivary  glands.  Tell  where 
these  are  situated,  and  the  duct  or  tube  through  which 
the  fluid  is  poured  into  the  mouth.  The  glands  of  the 
digestive  organs  make  substances  that  can  be  absorbed 
and  used  by  the  body.  The  substance  manufactured 
by  the  salivary  glands  changes  starch  into  sugar. 

Saliva  is  formed  and  poured  out  each  moment  in 
quantities  exactly  suited  to  the  nature  and  quantity 
of  the  food  that  is  being  chewed.  If  the  food  is  already 
moist,  the  quantity  of  saliva  produced  will  be  very 
small.  Why  ?  When  liquid  foods  like  milk  are  taken, 
little  or  no  saliva  will  be  produced.  Dry  and  highly 
flavored  foods  cause  the  salivary  glands  to  pour  out 
an  abundance  of  saliva.  Why  ?  Food  containing 
starch,  which  needs  the  action  of  saliva  to  digest 
it,  whether  moist  or  dry,  should  be  thoroughly  chewed. 
It  is  very  necessary  that  the  food  should  remain  in  the 
mouth  long  enough  for  a  sufficient  amount  of  saliva  to 
be  poured  out  upon  it,  and  that  it  should  be  so  thoroughly 
chewed  that  the  saliva  will  become  mingled  with  every 
part  of  it. 

Try  this :  Add  a  teaspoonful  of  saliva  to  a  table- 
spoonful  of  paste  prepared  from  corn  starch,  thoroughly 
mingling  the  saliva  with  the  paste.  If  this  is  kept 
warm,  at  a  temperature  of  about  blood  heat,  in  a  few 
minutes  the  thick  paste  will  have  become  almost  as 
thin  as  water,  and  in  a  short  time  a  sweet  taste  may 
be  readily  detected.  What  change  has  occurred  ? 


HOW  FOOD   BECOMES  LIVING  TISSUE       39 

The  process  of  starch  digestion  is  not  confined  to 
animals  alone.  Most  plants  are  capable  of  trans- 
forming starch  into  sugar.  This  change  always  takes 
place  in  the  ripening  of  fruits.  The  starch  of  the 
green  apple,  for  example,  is  changed  into  the  sweet, 
wholesome  flavors  found  in  the  ripe  fruit.  By  a  similar 
process,  the  starch  stored  up  by  the  roots  of  the  maple 
tree  in  the  fall  is  in  the  spring  converted  into  sugar 
and  carried  up  in  the  sap.  It  is  in  this  way  also  that 
the  honey  of  plants  is  formed  to  be  deposited  in  the 
flower  cups  from  which  it  is  collected  by  the  bee. 

When  the  food  has  been  sufficiently  acted  upon  in 
the  mouth,  it  is  then  passed  on  its  way  along  the 
alimentary  canal.  The  muscles  at  the  back  of  the 
mouth  seize  the  food  and  carry  it  into  the  gullet  or 
esophagus,  —  the  name  given  to  the  nine  inches  of  the 
food  canal  that  connects  the  mouth  with  the  stomach. 

The  muscles  at  the  back  of  the  mouth  seem  to  act 
as  gatekeepers  to  guard  the  entrance  to  the  esophagus. 
At  frequent  intervals  during  mastication,  they  move 
the  food  forward  in  the  mouth,  thus  keeping  it  there 
until  it  has  been  thoroughly  chewed,  when  they  are 
ready  to  let  it  pass  on.  The  food  then  seems  to 
"swallow  itself,"  without  any  effort  on  our  part. 
People  very  often  force  the  food  out  of  the  mouth  into 
the  esophagus  before  it  has  had  the  proper  mouth 
treatment.  If  the  act  of  swallowing  requires  a  con- 
scious effort,  we  may  be  sure  that  the  food  has  not 
been  long  enough  in  the  mouth. 


4o 


THE   BODY  IN  HEALTH 


The  esophagus  is  not  a  hollow  tube  through  which 
the  food  is  dropped  into  the  stomach.  The  walls  of 
the  entire  alimentary  canal  are  composed  in  part  of 
muscles,  arranged  in  such  a  way  as  will  best  assist  the 
work  of  the  different  digestive  organs.  By  means  of 

the  muscles  in  the 
esophagus,  the  food 
is  moved  along  until 
it  reaches  the  second 
food  station,  -  -  the 
stomach. 

To  form  the  stom- 
ach, the  food  tube  is 
widened  into  a  broad 
pouch,  as  shown  in 
the  picture.  At  each 
end  of  the  pouch  is 
a  strong  circular 
muscle  to  guard  the 
entrance  and  the  exit. 
The  entrance  is  called 
the  cardiac  opening, 
and  the  exit  is  called 
the  pylorus,  meaning 
the  "gatekeeper." 

The  large  end  of  the  stomach  near  the  cardiac  opening, 
where  digestion  chiefly  takes  place,  is  called  the  cardiac 
end ;  the  lower  and  narrower  end,  which  is  chiefly 
composed  of  very  strong  muscles,  is  the  pyloric  end. 


TRACE  THE  FOOD  INTO  THE  ESOPHAGUS. 

I,  tongue;  2,  pharynx;  3,  epiglottis;  4,  larynx 
5,  tracheae;  6,  esophagus. 


HOW  FOOD   BECOMES  LIVING  TISSUE       41 


ENTRANCE 


EXIT 


Even  before  the  food  reaches  the  stomach,   a  very 
important   work    of   preparation    has    been    going    on 
there.     Nature  has  installed  in  the  body,  to  help  on 
the  work  of  digestion,  a  kind  of  signaling  sys-  stomach 
tern  by  means  of  which  the  digestive  organs  are  digestion- 
given  notice  when  food  is  to  be  expected.     The  cell 
workers  then  at  once  begin  active  preparations  for  their 
work. 

You  have  noticed  I 

how,  at  the  mere 
sight  or  odor  of 
appetizing  food  - 
when  you  smell  a 
good  dinner  cook- 
ing, for  example  - 
the  mouth  begins  to 
"water."  This  is 
because  a  sort  of 
telegraphic  mes- 
sage has  been  sent 

from  the  brain  to  the  salivary  glands,  and  they  have 
immediately  begun  to  pour  out  a  quantity  of  saliva 
in  readiness  for  the  food  that  is  expected.  Some- 
thing of  the  same  kind  takes  place  also  in  the  stomach. 
A  Russian  scientist,  Professor  Pawlow,  made  many 
experiments  upon  dogs  and  men  by  means  of  which  he 
discovered  some  very  interesting  things  about  the  work 
of  digestion,  especially  that  part  of  the  work  that  is 
done  in  the  stomach.  He  made  an  arrangement  by 


THE   TWO    PARTS    OF  THE    STOMACH    AND   THE     EN- 
TRANCE   AND    EXIT. 


THE   BODY  IN  HEALTH 


which  he  could  actually  see  into  the  stomach  of  a  dog 
and  find  out  exactly  what  took  place  there.  When 
the  dog  was  hungry,  the  mere  sight  or  smell  of  food 
caused  the  stomach,  as  well  as  the  mouth,  to  secrete 
its  digestive  juice,  and  this  continued  all  the  while  the 
food  was  being  chewed.  By  the  time  the  food  actually 

reached  the  stomach,  there 
was  a  quantity  of  digestive 
juice  ready  for  it. 

The  digestive  juice  that  is 
poured  upon  the  food  while 
it  is  in  the  stomach  is  called 
gastric  juice.  It  makes  its 
first  appearance  upon  the 
walls  of  the  stomach  in  little 
drops,  like  tiny  beads  of  sweat 
upon  the  skin  when  the  per- 
spiration starts.  As  the  quan- 
tity increases,  the  drops  run 
together  and  trickle  down  the 
sides  of  the  stomach  in  little 
streams.  The  lining  mem- 
brane of  the  stomach,  seen 

under  a  microscope,  is  found  to  be  crowded  into 
minute  openings.  Each  of  these  openings  is  con- 
nected with  a  narrow  tube  which  extends  into  the 
walls  of  the  stomach,  making  a  kind  of  pocket.  This 
little  pocket  is  lined  with  living  cells,  which  during 
digestion  are  actively  at  work  making  the  gastric  juice. 


THREE   GASTRIC   GLANDS   (CARDIAC 
PORTION  OF  STOMACH). 


HOW  FOOD  BECOMES  LIVING  TISSUE      43 

The  gastric  juice  has  no  action  upon  starch,  sugar,  or 
fats,  but  only  digests  some  of  the  protein  of  the  food. 
There  are  two  digestive  substances  made  by  the  gastric 
glands,  —  pepsin  and  rennin,  which  are  called  ferments. 
The  principal  work  done  in  the  stomach  is  to  liquefy  the 
food.  The  rennin  in  the  gastric  juice  has  an  interest- 
ing work  to  perform  in  connection  with  the  digestion 
of  milk.  If  milk  were  to  remain  in  the  liquid  form  in 
which  it  is  swallowed,  it  would  pass  quickly  out  of  the 
stomach  without  digestion.  The  rennin  changes  the  milk 
into  insoluble  curds,  and  the  proteins  which  it  contains 
can  then  be  worked  upon  by  the  pepsin.  If  the  curds 
are  hard  and  tough,  the  work  will  be  harder  and  the 
milk  will  not  be  so  well  digested.  For  this  reason  it  is 
not  a  good  thing  to  swallow  milk  rapidly,  in  large 
quantities,  as  one  does  water.  A  nursing  babe  takes 
the  milk  in  small  quantities.  This  is  the  natural 
method  of  eating  milk,  in  small  sips,  which  will  then 
form  only  small  curds,  which  can  easily  be  acted  upon 
by  the  gastric  juice. 

The  flow  of  the  gastric  juice  is,  like  that  of  the 
saliva,  regulated  in  a  most  exact  manner,  both  in 
quantity  and  quality,  to  suit  the  foods  eaten.  Foods 
containing  a  large  amount  of  proteins  call  forth  an 
abundant  flow  of  gastric  juice,  whereas  starchy  and 
fatty  substances,  which  are  not  digested  in  the  stomach, 
do  not  excite  the  gastric  glands  to  lively  activity. 
Why? 

The  work  of  protein  digestion  which  goes  on  in  the 


44  THE   BODY   IN  HEALTH 

stomach  requires  acid.  Some  of  the  gastric  glands  pour 
out  a  very  strong  acid  called  hydrochloric  acid.  This 
acid,  while  it  assists  the  work  of  stomach  digestion, 
puts  an  end  to  the  work  of  starch  digestion  which  was 
begun  in  the  mouth  by  the  saliva  mixed  with  the 
food.  As  soon  as  the  food  becomes  thoroughly  mixed 
with  the  gastric  juice,  which  is  about  an  hour  after 
it  enters  the  stomach,  the  digestion  of  the  starch, 
which  has  been  going  on  up  to  that  time,  ceases.  The 
acid  in  the  gastric  juice  also  does  the  important  work 
of  destroying  bacteria  or  germs  that  get  into  the 
stomach  through  the  mouth.  So  the  stomach  is  a  kind  of 
disinfecting  room  for  protecting  the  body  against  germs. 

We  found  in  the  mouth  not  only  the  chemical  action 
of  the  saliva,  but  also  the  muscular  action  of  the  jaws 
and  the  tongue.  The  work  of  the  stomach  is  also 
assisted  by  the  muscles.  Next  to  the  lining  mem- 
brane which  contains  the  gastric  glands  is  a  coat  of 
muscular  tissue.  By  contracting  these  muscles,  the 
stomach  is  able  to  change  its  size  and  shape  and  to 
produce  a  sort  of  kneading  action  upon  the  food,  thus 
softening  it  and  thoroughly  mingling  it  with  the  gastric 
juice.  This  work  is  kept  up  until  the  whole  mass  is 
soft  and  is  something  like  a  thick  soup. 

As  more  and  more  gastric  juice  is  poured  into  the 
stomach,  the  food  there  becomes  more  and  more  acid. 
This  acid  urges  the  muscles  of  the  stomach  to  work 
with  greater  and  greater  vigor.  The  gastric  acid  also 
causes  the  pylorus  to  open  when  the  food  has  been 


HOW  FOOD  BECOMES  LIVING  TISSUE      45 

properly  acted  upon  by  the  stomach  juices.  The 
pylorus  does  not  allow  food  that  is  not  in  proper 
condition  to  pass.  Any  solid  particles  that  get  down 
near  the  exit  are  pushed  back  by  the  gastric  muscles 
to  the  cardiac  end  of  the  stomach  for  further  diges- 
tion. The  food  begins  passing  from  the  stomach  within 
a  few  minutes  after  taking  a  meal.  At  brief  intervals 
the  pylorus  opens  and  passes  out  a  small  amount  of 
liquid  food.  At  the  end  of  four  or  five  hours,  the 
stomach  is  completely  emptied. 

When  the  food  passes  through  the  pylorus,  it  enters 
the  next  and  most  important  of  the  digestive  organs, 
the  small  intestine,  which  is  the  third  food  station. 
The  contact  of  the  acid  liquid  with  the  mucous  lining 
of  the  intestine  causes  the  pylorus  to  close.  The  action 
of  the  gastric  acid  in  both  opening  and  closing  the 
pylorus  is  one  of  the  most  remarkable  and  interesting 
things  known  about  the  body. 

This  small  intestine  is  a  slender  tube,  about  twenty 
feet  long,  that  passes  from  the  stomach  to  the  large 
intestine  or  colon.  You  can  see  in  the  illustration  the 
curious  way  in  which  this  long  tube  is  coiled  and 
packed  in  the  part  of  the  body  it  occupies. 

We  have  already  studied  the  work  of  two  of  the 
five  digestive  fluids.  Which  two  ?  The  three  T 

.  to.          .    .  ,  r       ,    Digestion 

remaining  juices  are  poured  upon  the  food  in  the 
while  it  is  in  the  small  intestine. 


One  of  these  is  poured  out  by  the  intestine 
itself  and  is  called  intestinal  juice.     The  other  two  are 


46 


THE   BODY  IN  HEALTH 


manufactured    by  two    large   organs    lying    near    the 
stomach,  the  liver  and  the  pancreas. 

The  fluid  manufactured  by  the  liver  is  the  bile, 
which  is  stored  up  in  a  sack  or  pouch  called  the  gall 
bladder.  When  needed  for  the  work  of  digestion, 

the  bile  is  poured 
through  a  duct  into 
the  small  intestine, 
in  much  the  same 
way  as  the  saliva  is 
poured  out  into  the 
mouth.  The  duct 
enters  the  intestine 
a  few  inches  below 
the  stomach. 

Up  to  this  point 
in  the  work  of  diges- 
tion, the  starch  has 
been  acted  upon  by 
the  saliva,  and  the 
proteins  by  the  gas- 
tric juice,  but  no 
change  has  taken 
place  in  the  fats,  except  that  they  have  been  melted  by 
the  heat  of  the  body.  The  special  work  of  the  bile  is  to 
aid  in  the  digestion  of  the  fats.  Fats  are  first  emulsified 
or  subdivided  into  particles  so  small  that  they  may 
be  absorbed.  An  emulsion  may  be  made  experimentally 
by  mixing  olive  oil  with  a  quantity  of  gum  water.  Add 


WHERE   THE  INTESTINAL   JUICE  is  MANU- 
FACTURED. 


HOW  FOOD  BECOMES  LIVING  TISSUE      47 

toone  part  of  mucilage  three  or  four  parts  of  watet ,  shake 
until  well  mixed,  and  then  add  one  part  oi  oil.  Note 
that  when  the  oil  is  first  added,  the  two  liquids  remain 
distinct.  Shake  thoroughly  for  a  minute,  when  it  will 
be  impossible  to  distinguish  the  oil  from  the  gum  water. 
The  result  will  be  a  creamy  liquid,  which,  added  to 
water,  produces  a  mixture  having  a  milky  appearance. 
If  allowed  to  stand  for  awhile,  the  emulsion  will  rise 
to  the  top  as  cream  rises  upon  milk. 

Next  the  fats  are  changed  into  soaps  by  combining 
with  the  alkaline  substances  of  the  bile  and  pancreatic 
juice.  In  the  form  of  soaps,  the  fats  are  soluble  and  can 
be  absorbed.  After  absorption,  the  soaps  are  changed 
back  into  fats. 

The  digestive  fluid  formed  by  the  pancreas/  the 
pancreatic  juice,  enters  the  intestine  at  the  same 
point  as  the  bile.  The  remarkable  thing  about  the 
pancreatic  juice  is  that  it  does  the  work  of  all  the 
other  juices  combined.  It  digests  starch,  like  the 
saliva ;  it  digests  proteins,  like  the  gastric  juice ;  and 
it  acts  upon  fats,  as  does  the  bile.  Why  should  there 
be  this  arrangement  in  the  food  canal,  do  you  think  ? 

The  work  of  the  saliva  ceases  when  the  food  becomes 
mixed  with  the  acid  juice  in  the  stomach.  When  it 
passes  out  into  the  small  intestine,  the  work  of  starch 
digestion  is  taken  up  again  and  carried  on  by  the 
pancreatic  juice. 

The  work  of  the  gastric  juice  also  ceases  when  the 
food  leaves  the  stomach,  because  the  acid  which  is 


48  THE   BODY  IN  HEALTH 

necessary  for  protein  digestion  is  neutralized  by  the 
alkaline  juices  of  the  intestine.  The  work  that  was 
being  done  by  the  pepsin  is  then  taken  up  and  com- 
pleted by  the  pancreatic  juice  and  the  other  juices  of 
the  intestine. 

The  pancreatic  juice  is  of  great  importance,  because, 
as  we  see,  it  acts  upon  each  of  the  three  great  classes 
of  food  substances,  —  carbohydrates,  proteins,  and 
fats.  The  other  two  juices  in  the  small  intestine,  the 
bile  and  the  intestinal  juice,  are  simply  aids  to  the 
work  of  the  pancreatic  juice. 

The  powerful  pancreatic  juice  is  poured  out  near 
the  entrance  to  the  small  intestine,  so  that  the  digestive 
work  to  be  done  there  is  well  started.  It  is  completed 
by  the  intestinal  juice,  which  is  poured  out  along  the 
whole  twenty  feet  of  the  intestine  and  does  much  the 
same  kind  of  work  as  the  pancreatic  juice.  In  addition 
to  this,  the  intestinal  juice  has  also  the  power  of 
digesting  cane  sugar. 

While  this  important  work  of  digestion  is  taking 
place  in  the  small  intestine,  another  interesting  work 
of  equal  importance  is  being  carried  on  there.  If  we 
examine  the  mucous  membrane  lining  of  the  small 
intestine,  we  find  that  it  contains,  like  the  stomach, 
the  little  tubelike  glands  that  made  the  digestive 
fluid  and  in  addition  to  these  a  thick  covering  with 
tiny  fingerlike  projections  which  give  it  a  velvety  ap- 
pearance. These  villi,  as  they  are  called,  have  a  very 
important  work  to  do.  They  suck  up  the  digested 


HOW  FOOD  BECOMES  LIVING  TISSUE      49 


food,  much  as  the  tiny  rootlets  of  a  plant  suck  up  its 
nourishment  from  the  soil.  Indeed,  the  villi  may  be 
properly  regarded  as  the  " roots"  of  the  body,  while  the 
liquid  food  which  bathes  the  villi  is  the  "soil"  out  of 
which  the  body  draws  its  sustenance  just  as  a  tree  or 
plant  grows  out  of  the  earth. 

We  have  already  learned  that  all  the  digested  food 
must  be  absorbed  through  the  walls  of  the  alimentary 
canal.  The  absorbing  surface  of  the  small  intestine, 


WHAT  WORK  DO  THESE  VILLI  PERFORM  ? 


DO  YOU  SEE  HOW  GREATLY 
THESE  VILLI  ENLARGE  THE 
ABSORBING  SURFACE  OF  THE 
INTESTINE  ? 


where  this  work  of  absorption  chiefly  takes  place,  is 
very  greatly  increased  by  the  villi  and  by  folds  in  the 
lining  membrane.  The  length  of  the  small  intestine 
is  about  twenty  feet,  and  its  circumference  about  three 
inches,  dimensions  which  would  give  an  absorbing  sur- 
face of  about  five  square  feet.  By  the  villi  and  the 
folds  in  the  mucous  membrane  it  is  increased  more 
than  fivefold  and  gives  an  absorbing  surface  of  many 
square  feet. 


50  THE  BODY  IN  HEALTH 

The  work  of  digestion  and  absorption  going  on  in 
the  small  intestine  is  greatly  helped  by  the  muscles,  as 
we  have  found  to  be  the  case  in  the  mouth  and  the 
stomach.  Like  the  stomach,  the  intestine  has  a  coat 
of  muscular  tissue  next  to  the  mucous  membrane.  By 
the  work  of  these  muscles,  the  food  is  kept  in  constant 
motion,  so  that  it  becomes  thoroughly  mixed  with  the 
digestive  juices,  and  the  villi  are  dipped  down  into  all 
parts  of  it  to  suck  up  the  digested  portion.  From  the 
stomach  downward,  the  food  is  moved  along  the  ali- 
mentary canal  by  successive  contractions  of  the  mus- 
cular walls  of  the  intestines.  These  contractions  are 
known  as  peristaltic  movements,  and  they  occur  with 
great  regularity  during  digestion.  You  can  illustrate 
intestinal  movement  by  filling  some  rubber  tubing  with 
water  and  tying  both  ends.  Press  the  tube  with  the 
fingers  of  each  hand  grasping  the  tube,  slowly  and  alter- 
nately. Peristaltic  movement  may  be  illustrated  by  run- 
ning a  finger  slowly  along  the  whole  length  of  the  tube. 

The  indigestible  materials  in  the  food,  as  well  as 
the  wastes  formed  during  digestion  and  any  of  the 
The  last  digested  food  that  still  remains,  is  carried  from 
food  the  small  intestine  into  the  large  intestine, 

which  is  not  a  digestive  organ  but  simply  a 
reservoir,  where  the  food  remains  until  all  of  the 
digested  portion  has  been  absorbed  from  it.  As  the 
liquid  food  is  sucked  up,  the  residue  becomes  more 
and  more  solid,  and  the  wastes  are  moved  onward 
until  they  are  ready  to  leave  the  body. 


HOW  FOOD  BECOMES  LIVING  TISSUE       51 

To  prevent  the  wastes  from  passing  back,  nature  has 
provided  at  the  end  of  the  small  intestine  a  check  valve 
known  as  the  ileocecal  valve.  This  valve  behaves  very 
much  like  the  pylorus.  It  passes  the  food  residues  and 
wastes  into  the  colon,  and  then  prevents  their  return 
to  the  small  intestine.  Sometimes  this  valve  becomes 
damaged,  and  then  the  filth  from  the  colon  passes  back 
into  the  small  intestine,  and  great  harm  results. 

If  the  work  of  digestion  has  been  well  done,  these 
wastes  will  pass  naturally  out  of  the  body  at  regular 
intervals.  The  emptying  of  the  bowels  takes  place 
normally  about  once  in  twenty-four  hours,  at  about 
the  same  time  each  day.  It  is  very  easy  to  form 
habits  in  this  respect  and  of  great  importance  that 
the  habits  we  form  should  be  good  ones.  It  is  just  as 
important  to  discharge  from  the  body  the  waste  prod- 
ucts as  it  is  to  take  in  a  fresh  supply  of  food.  If  the 
drains  of  a  city  become  choked  up,  the  health  of  the 
community  is  very  likely  to  suffer.  The  health  of  the 
cell  community  which  inhabits  the  human  body 
depends  upon  the  prompt  removal  of  all  wastes. 

Besides  the  changes  which  are  made  in  the  food  in 
the  intestines  by  the  digestive  juices,  there  are  other 
changes  which  are  produced  by  microbes.     We  The 
saw  that  the  acid  gastric  juice  destroyed  the  work  of 
germs   that   found   entrance   to   the   healthy  microbes- 
stomach.     The  intestinal  juices  are  not  acid,  so  the 
germs   have   a   chance   to  grow  and   multiply   there. 
They  gradually  increase  in  number  from  the  stomach 


52  THE   BODY  IN  HEALTH 

to  the  large  intestine,  which  is  a  very  favorable  breed- 
ing place  for  germ  colonies.  Some  of  these  are  not 
only  harmless,  but  even  friendly  and  useful.  Others, 
however,  cause  the  contents  of  the  intestine  to  decay 
or  putrefy  and  give  off  very  offensive  odors  and  poison- 
ous products  that  are  most  injurious  to  the  cells.  In 
a  person  who  is  in  perfect  health  and  who  lives  whole- 
somely, these  poison-forming  germs  are  not  present  in 
sufficient  numbers  to  do  harm.  But  under  certain 
conditions,  especially  in  one  who  lives  unhealthfully, 
they  may  multiply  to  a  very  great  extent,  and  the 
poisons  they  produce  may  be  a  cause  of  serious  disease. 
In  all  cases,  the  prompt  removal  of  the  waste  matters 
in  the  intestine  is  a  matter  of  great  importance.  Head- 
aches and  general  bad  feelings  and  bad  temper  may 
result  from  the  body's  being  poisoned  by  the  waste 
matters  that  have  been  allowed  to  remain  in  it  beyond 
the  natural  time. 

The  digested  food  which  has  been  sucked  up  by  the 
walls  of  the  alimentary  canal,  in  much  the  same  way 
as  a  sponge  absorbs  water,  is  in  the  process  of  absorp- 
tion changed  into  blood.  It  then  passes  into  the 
blood  vessels  with  which  the  walls  of  the  canal  are 
richly  supplied. 

Before  the  food  supply  in  the  blood  passes  to  the 
heart,  from  which  it  is  to  be  distributed  to  the  body 
for  the  use  of  the  cells,  it  must  pass  to  the  liver  for  its 
final  inspection  and  preparation.  Some  starch,  which 
during  digestion  was  converted  into  sugar,  is  changed 


HOW   FOOD   BECOMES   LIVING  TISSUE       53 

back  by  the  liver  into  a  kind  of  animal  starch  called 
glycogen.  In  this  form  it  is  stored  up  in  the  tissues 
of  the  liver  until  it  is  needed  for  body  work  or  heat 
production,  when  it  is  given  out  as  needed,  having 
been  first  changed  back  into  sugar.  In  this  respect, 
the  liver  might  be  looked  upon  as  a  sort  of  living, 
automatic  stoker,  which  supplies  fuel  to  the  body  as 
needed,  just  as  devices  made  for  the  purpose  supply 
coal  as  needed  to  the  furnaces  of  steam  boilers. 

The  liver  also  acts  as  a  kind  of  food  inspector  for 
the  purpose  of  protecting  the  body  against  poisons. 
When  any  metallic  poison  such  as  mercury,  lead,  or 
arsenic  is  taken  into  the  blood,  the  liver  absorbs  and 
retains  as  much  as  possible  of  the  poison  and  so  pro- 
tects the  rest  of  the  body.  Vegetable  poisons  are  also 
destroyed  by  the  liver. 

We  should  notice  as  we  pass  that  not  all  of  the  food 
supply  passes  through  the  liver  on  its  way  to  the  heart. 
A  comparatively  small  portion,  especially  that  which 
contains  the  digested  fats,  is  taken  from  the  intestines 
by  small  vessels  called  lacteals,  which  carry  it  to  a 
duct  called  the  thoracic  duct,  by  which  it  is  carried 
directly  to  the  heart. 

The  final  act  of  becoming  nourished  is  the  making 
of  the  liquid  blood  into  solid  tissues,  a  change  exactly 
the  reverse  of  that  which  takes  place  in  diges-  Making 
tion.     Each  tissue  takes  from  the  blood  the  blood  into 
material  needed  for  its  own  uses  and  builds  tissues- 
and  repairs  itself.     So  you  see  that  assimilation,  for 


54  THE   BODY  IN  HEALTH 

that  is  what  this  process  is  called,  is  something  like 
creation.  It  is  the  building  of  tissues  and  organs 
out  of  the  blood,  the  stream  of  life,  which  serves  as  a 
sort  of  circulating  market,  or,  one  may  say,  a  canal 
along  which  the  nutrient  elements  prepared  in  the 
digestive  organs  are  conveyed  to  the  places  where 
they  are  needed. 

Let  us  now  retrace  briefly  the  chain  of  events  which 
follow  each  other  in  the  work  of  digestion,  from  the 
time  the  food  enters  the  body  until  it  becomes  a  part 
of  it,  built  into  its  living  tissue. 

In  the  mouth  the  food  is  ground  and  crushed  into  a 
pulp  and  thoroughly  moistened  with  saliva,  which 
begins  the  digestion  of  starch. 

It  then  passes  through  the  esophagus  into  the 
stomach,  which  is  a  sort  of  storehouse  or  preparatory 
chamber,  where  it  is  disinfected,  and  the  work  of  pro- 
tein digestion  begins. 

Having  been  thoroughly  worked  upon  by  the  gastric 
juice  and  the  stomach  muscles,  it  is  passed  out  through 
the  pylorus  into  the  small  intestine.  Here  the  bile 
formed  in  the  liver  is  poured  upon  it  for  the  digestion 
of  fats.  The  pancreas  also  contributes  its  powerful 
juice,  which  works  upon  all  three  classes  of  foods, 
starches,  fats,  and  proteins.  The  intestinal  juice  also 
does  much  the  same  work  as  the  pancreatic  juice, 
and  in  addition  it  digests  cane  sugar. 

By  means  of  the  villi  lining  the  intestinal  wall,  the 
digested  food  is  absorbed,  as  the  food  is  worked  upon 


HOW  FOOD   BECOMES  LIVING  TISSUE       55 

and  carried  along  by  the  muscles  to  the  large  intestine, 
where  the  absorption  of  the  digested  food  is  completed 
and  the  waste  matters  are  discharged  from  the  body. 

The  absorbed  food  is  carried  by  the  blood  vessels 
to  the  liver,  which  puts  the  finishing  touches  on  the 
proteins  or  building  foods,  and  regulates  the  supply 
of  fuel  foods  to  the  body,  storing  up  digested  starch 
in  the  form  of  glycogen.  The  liver  also  extracts 
poisons  and  changes  them  into  less  harmful  sub- 
stances. 

The  food  supply  then  passes  to  the  heart,  from  which 
it  is  sent  out  into  every  part  of  the  body  and  used  by 
the  cells,  for  the  building  up  of  the  living  tissues  and 
organs  which  compose  the  body. 

HEALTH  PROBLEMS 

1.  Mention  at  least  ten  insoluble  articles  that  can  be  digested 
and  explain  how  digestion  is  possible. 

2.  What  is  the  meaning  of  canal  ?     Is  it  proper  to  speak  of  the 
tube  that  carries  the  food  through  the  body  as  a  canal  ?     Why  ? 

3.  Which  of  your  permanent  teeth  have  you  now?     Which  of 
your  baby  teeth  are  you  losing  ?     What  permanent  teeth  must  you 
still  get  ? 

4.  Just  where  on  the  tongue  are  the  taste  buds  situated  ?     What 
would  happen  to  one  if  his  taste  buds  should  be  destroyed  ? 

5.  Have  you  ever  had  a  sickness  during  which  your  mouth 
seemed  "dry"  so  that  you  could  not  moisten  your  food  well? 
How  did  the  food  taste  ?     Explain. 

6.  Do  people  who  masticate  their  food  thoroughly  get  more 
pleasure  from  it  than  those  who  bolt  it,  or  swallow  it  in  a  half- 
masticated  condition  ?     Explain. 


56  THE   BODY  IN  HEALTH 

7.  Have  you  ever  noticed  that  when  you  are  sick  food  will  not 
make  your  mouth  water  ?     What  is  the  explanation  of  this  ? 

8.  Mention  some  appetizing  foods.     Mention  some  that  are 
not  appetizing.     Which  can  you  digest  most  easily  ?     Why  ? 

9.  Do  you  know  why  people  often  crave  acid  drinks,  as  lemon- 
ade and  the  like  ?     Would  you  expect  these  to  assist  digestion  ? 
Why? 

10.  Write  a  little  story  about :  "What  Happens  to  a  Mouthful 
of  Bread."  Take  it  right  at  the  start  and  show  what  interesting 
things  occur  until  the  body  is  through  with  it. 

REVIEW  QUESTIONS 

1.  What  work  is  necessary  in  order  to  prepare  nutrients  so  they 
can  be  used  by  the  cells  as  food  ? 

2.  Compare  the  organs  used  in  digestion  with  the  workers 
in  a  bakery  establishment. 

3 .  What  is  the  name  of  the  canal  through  which  the  food  passes 
in  the  body  ?    What  are  its  principal  parts  ? 

4.  What  are  the  digestive  juices  ?    How  many  kinds  are  there  ? 

5.  Of  what  does  the  work  of  digestion  consist  ? 

6.  What  does  it  mean  to  masticate  one's  food  ?    Why  is  masti- 
cation necessary  ? 

7.  How  many  teeth  does  an  adult  have  ?    Describe  each  kind 
and  tell  for  what  it  is  used. 

8.  What  is  the  saliva,  where  is  it  formed,  and  what  is  its  use  ? 
What  is  necessary  in  order  that  saliva  may  get  in  touch  with  one's 
food  ? 

9.  What  are  the  enzymes  and  for  what  are  they  used  in  the 
body  ? 

10.  Can  starch  be  digested  by  plants  as  well  as  by  animals? 
How  can  one  tell  ? 

n.  If  one  has  poorly  masticated  his  food,  will  he  have  to  make 
an  effort  to  swallow  it  ?  Why  ? 


HOW  FOOD   BECOMES   LIVING  TISSUE       57 

12.  How  is  the  stomach  formed  ? 

13.  What  is  the  meaning  of  pylorus  ? 

14.  Describe  the  "signal  system"  which  nature  has  provided  in 
the  body  to  help  digestion. 

15.  What  happens  in  the  mouth  when  one   sees  or  smells 
appetizing  food  ?     How  does  this  help  digestion  ? 

1 6.  What  juice  is  mixed  with  the  food  in  the  stomach  ? 

17.  Suppose  you  should  examine  the  lining  membrane  of  the 
stomach,  what  should  you  see  ? 

1 8.  How  is  the  amount  of  gastric  juice  prepared  in  the  stomach 
adapted  to  the  needs  of  digestion  ?     What  is  the  use  of  this  acid  ? 

19.  Describe  the  muscular  action  of  the  stomach.     How  does 
this  help  digestion  ? 

20.  Describe  the  work  of  the  pylorus. 

21.  How  long  does  it  take  ordinarily  for  a  meal  to  pass  out  of 
the  stomach  ? 

22.  Where  is  the  small  intestine  ?     How  many  juices  are  poured 
out  on  the  food  from  the  intestine  ? 

23.  What  organs  make  the  bile  ? 

24.  Where  are  the  fats  of  our  food  digested  ?     How  are  they 
digested  ? 

25.  What  is  the  pancreatic  juice  ?    What  foods  will  pancreatic 
juice  digest  ? 

26.  Describe  the  villi  in  the  mucous  membrane  of  the  small 
intestine.     What  is  their  business  ? 

27.  What  is  the  large  intestine  ?     How  does  it  differ  from  the 
small  intestine  in  its  work  ? 

28.  Before  the  food  in  the  blood  passes  to  the  heart,  where  must 
it  go  for  final  inspection  ? 

29.  Just  what  does  the  liver  do  to  the  food  to  make  it  ready  for 
use  by  the  cells  ?    Why  is  it  right  to  speak  of  the  liver  as  a  kind 
of  food  inspector  ? 

30.  What  is  the  meaning  of  assimilation  ? 


CHAPTER  IV 
EATING  FOR  HEALTH  AND  PLEASURE 

THE  only  part  of  the  important  work  of  nutrition 
that  Nature  has  left  to  us  is  the  selection  of  the  food 
and  the  preparation  of  it  for  digestion  by  thorough 
chewing.  All  the  rest  of  the  work  is  done  for  us,  with- 
out any  thought  or  effort  on  our  part.  Everything 
done  in  the  process  of  digestion,  however,  is  greatly 
influenced  by  the  manner  in  which  we  do  our  part  of 
the  work. 

As  an  aid  to  us  in  selecting  the  food  and  as  an  in- 
ducement to  us  to  keep  it  in  the  mouth  until  our  part 
of  the  work  is  well  done,  Nature  has  put  into  it  all 
kinds  of  agreeable  flavors.  When  we  swallow  our 
foods  with  little  or  no  chewing,  do  you  think  we  lose 
these  flavors  and  miss  the  pleasure  that  Nature  in- 
tended for  us  in  eating  and  that  is  a  great  help  to  the 
work  of  digestion  ? 

One  of  Professor  Pawlow's  interesting  experiments 
proved  that  the  amount  and  efficiency  of  the  gastric 
juice  depend  very  much  upon  the  enjoyment  of  the 
food.  The  esophagus  of  a  dog  was  divided  and  part 
of  it  connected  with  a  tube.  When  the  dog  was  fed, 
the  food,  instead  of  passing  into  the  stomach,  dropped 

58 


EATING  FOR  HEALTH  AND  PLEASURE      59 

out  through  the  opening  into  a  dish.     The  dog,  how- 
ever, thought  he  was  having  a  good  meal,  and  the 
gastric  juice  immediately  began  to  form  in    ' 
the  stomach  and  continued  to  pour  out  as  tion  de- 
long  as  he  kept  on  eating  and  enjoying  the  pendsupon 
food.     When  he  was  given  food  that  he  did  $££** 
not  like,  however,  there  was  no  outpouring  of 
gastric  juice.     Also  when  food  was  put  into  the  dog's 
stomach  through  the  opening,  without  his  knowledge, 
little  gastric  juice  was  formed  and  the  food  lay  there 
for  hours  undigested. 

The  gastric  juice  that  is  poured  out  at  the  beginning 
of  digestion,  as  the  result  of  the  enjoyment  of  the  food, 
has  been  given  the  name  of  "appetite  juice  "  and  has 
been  found  to  be  the  most  powerful  and  active  juice 
formed  in  the  stomach.  We  can  see  from  this  that 
the  more  the  food  is  enjoyed,  the  better  it  will  be 
digested.  If  a  person  is  not  hungry  and  so  does  not 
relish  his  food,  he  will  have  no  "appetite  juice"  to 
welcome  the  food  in  the  stomach  and  to  begin  the 
digestive  process. 

Do  you  think  it  is  of  great  importance  that  the  food 
should  be  attractive  to  the  eye  and  savory  to  the  smell 
and  taste  ?  Why  ?  Should  each  mouthful  be  kept 
in  the  mouth  until  all  the  enjoyment  possible  has  been 
got  out  of  it  ?  Why  ? 

Those  who  wish  to  keep  the  body  in  the  best  state 
of  health  should  cultivate  the  habit  of  chewing  the  food 
until  all  the  soluble  parts  have  been  dissolved.  As  a 


60  THE   BODY  IN  HEALTH 

rule,  this  will  be  until  enough  saliva  has  been  poured 
out  to  extract  from  the  food  all  the  substances  having 
any  taste.  In  other  words,  we  should  chew  the  food 
until  we  have  got  all  the  taste  out  of  it. 

Mouth  digestion  we  have  found  to  be  the  first  of  a 
number  of  changes  which  take  place  in  the  alimentary 
canal.  If  the  first  step  is  imperfect,  the  succeeding 
steps  are  likely  to  be  more  or  less  defective.  Stomach 
digestion  can  not  be  well  performed  unless  mouth 
digestion  is  well  done.  As  you  know,  the  stomach 
has  no  teeth  by  means  of  which  it  can  crush  and  grind 
any  lumps  of  food  that  have  been  forced  down  into  it. 
When  the  food  is  not  thoroughly  masticated,  it  must 
remain  in  the  stomach  longer  than  it  should,  while 
the  stomach  muscles  try  to  perform  the  work  that 
should  have  been  done  by  the  teeth.  The  gastric 
juice,  which  by  its  acidity  destroys  germs,  after  a  time 
disappears.  There  is  then  no  protection  against  germs 
that  may  enter  the  stomach  through  the  mouth.  The 
undigested  material  will  afford  food  for  the  germs,  and 
they  will  multiply  very  rapidly,  causing  the  food  to 
ferment  or  putrefy.  The  formation  of  large  quantities 
of  gases  and  acids  results.  Colic,  biliousness,  jaundice, 
and  other  serious  maladies  are  caused  in  this  way. 

The  bolting  of  food,  or  swallowing  it  without  proper 
Some  •  attention  to  mastication,  is  a  very  injurious 
causes  of  though  common  habit.  Many  of  us  are  in 
indigestion.  ^^  a  hurry  that  we  prefer  to  make  use 
of  soft  foods  of  some  sort  that  can  be  easily  swal- 


EATING  FOR  HEALTH  AND   PLEASURE     61 


lowed  without  chewing.  Moist  foods  such  as  mushes 
and  soups  cause  the  flow  of  only  a  small  part  of  the 
saliva  that  is  called 
forth  by  the  same 
food  in  a  dry  state. 
It  is  therefore  bet- 
ter that  much  of 
our  food  should  be 
taken  dry  so  as  to 
compel  thorough 
mastication. 

It  should  be 
remembered,  how- 
ever, that  in  tak- 
ing starchy  foods 
which  are  already 
moist,  mastication 
is  all  the  more 
necessary  for  the 
development  of 
the  amount  of 

saliva  required  for  the  digestion  of  the  starch.  Even 
such  liquid  foods  as  vegetable  soups  or  gruels  should 
be  held  in  the  mouth  until  thoroughly  mingled  with 
the  saliva.  In  the  feeding  of  horses,  farmers  recog- 
nize the  value  of  thorough  mastication.  To  secure 
this,  they  frequently  put  into  the  manger  along 
with  the  food  a  quantity  of  small  .stones.  The  ani- 
mal is  then  compelled  to  take  the  food  into  its 


WHAT  is  LIKELY  TO  HAPPEN  TO  ONE  WHO  GULPS 

HIS    FOOD    AS   THIS    BOY    IS    DOING  ? 


62  THE   BODY  IN  HEALTH 

mouth  in  such  small  quantities  that  hasty  eating  is 
prevented. 

Drinking  at  meals  usually  leads  to  bolting  food. 
These  two  evils  are  closely  connected.  Liquids  taken 
with  the  food  diminish  the  flow  of  saliva  and  so  inter- 
fere with  the  work  of  digestion.  Why  ?  Very  cold 
liquids  are  especially  bad,  because  they  lower  the 
temperature  of  the  stomach  too  much  and  put  a  stop 
to  the  digestive  process.  A  temperature  of  100  degrees 
is  required  for  digestion.  It  has  been  observed  that 
a  glassful  of  ice  water  lowered  the  temperature  of  the 
stomach  contents  to  70  degrees  and  that  more  than 
half  an  hour  passed  before  the  normal  temperature 
was  regained.  Hence  the  whole  digestive  process  was 
checked  for  half  an  hour.  An  equal  quantity  of  ice- 
cream would  have  produced  a  much  more  marked 
effect. 

Hot  drinks,  while  they  excite  the  stomach,  tend  to 
relax  and  weaken  its  muscles  and  lessen  digestive  vigor. 
They  also  destroy  certain  useful  elements  in  the  saliva. 
The  highest  degree  of  digestive  activity  seems  to  be 
secured  by  the  use  of  food  at  a  temperature  a  little 
below  that  of  the  body,  or  at  the  ordinary  temperature. 

The  best  time  to  take  liquids  is  at  the  close  of  the 
meal,  when  there  will  be  little  danger  of  drinking  too 
much.  Fruits  eaten  with  the  meal,  or  at  the  close, 
lessen  the  necessity  of  drinking  too  much  at  meals. 

It  is  not  well  to  try  to  get  along  without  any  liquids 
when  we  eat  a  meal  of  solid  food.  Experiments  have 


EATING  FOR  HEALTH  AND  PLEASURE     63 

shown  clearly  that  a  glassful  of  water,  not  too  cold, 
taken  with  the  meal,  helps  digestion  and  enables  one 
to  get  more  out  of  his  food.  A  good  plan  is  to  take  a 
glassful  of  cool  water  a  half  hour  before  a  meal,  and  a 
glassful  at  the  close. 

A  variety  of  foods  is  necessary  to  assist  the  appetite, 
upon  which  good  digestion  so  largely  depends.  The 
stomach  may,  however,  easily  be  overworked  by  a 
great  variety  of  foods  taken  at  a  single  meal. 

Simplicity  is  very  important  for  good  digestion.  The 
natural  appetite  is  easily  satisfied  with  a  small  number 
of  foods,  simply  and  wholesomely  prepared.  Animals 
such  as  the  sheep,  the  goat,  and  the  cow,  which  in  the 
course  of  a  morning's  grazing  may  swallow  one  hundred 
different  kinds  of  herbs,  have  very  complicated  stomachs 
with  four  compartments.  Some  fishes  which  live  on 
others  are  provided  with  more  than  half  a  dozen  stomachs 
in  which  to  do  their  digestive  work.  Man,  with  a  single, 
simple  stomach,  often  sits  down  to  a  feast  which  would 
tax  the  digestive  power  of  an  animal  having  many 
stomachs. 

It  is  important  that  the  food  should  be  varied  from 
day  to  day  or  at  different  meals  as  each  food  supplies 
the  body  with  some  special  useful  product. 

The  digestion  of  a  meal  requires  at  least  several 
hours.     As  you  might  expect,  the  stomach  then  needs 
a  period  of  rest  before  it  is  ready  to  under-  A  tired 
take    the    digestion    of    another    meal.     Of  stomach, 
course,  if  food  is  taken  too  frequently,  the  stomach 


64  THE  BODY  IN  HEALTH 

will  suffer  sooner  or  later,  because  it  will  have  no  rest. 
You  know  that  the  muscles  of  the  arm  become  wearied 
by  constant  exercise  and  so  do  the  stomach  muscles, 
which  are  actively  exercising  during  digestion.  "A 
tired  stomach  is  a  weak  stomach."  When  the  stomach 
feels  "faint,"  rest  is  what  is  needed,  yet  many  people 
insist  on  putting  more  food  into  it,  thus  compelling 
it  to  work  when  it  ought  to  be  allowed  to  rest.  Suppose 
this  is  kept  up ;  what  may  happen  to  the  stomach  ? 
Have  you  known  of  such  cases  ? 

If  a  meal  is  taken  before  the  preceding  meal  has 
been  digested  and  has  passed  from  the  stomach,  the 
portion  remaining  becomes  mixed  with  the  fresh  food, 
and  being  too  long  in  the  stomach,  it  is  liable  to  ferment. 
Thus  the  whole  mass  of  the  food  is  more  or  less  spoiled 
and  rendered  unfit  for  the  nourishment  of  the  body. 
What  is  still  worse,  the  stomach  is  liable  to  suffer  great 
injury  from  the  acids  developed. 

The  number  of  meals  needed  daily  depends  upon 
the  age  and  upon  the  nature  and  quantity  of  the  food 
taken  at  the  meals.  A  little  baby,  that  takes  only  a 
small  quantity  of  easily  digested  food  at  each  meal, 
requires  food  at  frequent  intervals.  As  it  gets  larger 
and  its  meals  increase  in  size,  the  interval  between 
meals  should  be  lengthened.  By  the  time  it  gets  its 
teeth  and  is  able  to  eat  solid  food,  three  meals  a  day 
are  quite  sufficient. 

The  great  majority  of  people  in  the  world  eat  only 
two  meals  a  day.  This  is  the  custom  of  the  natives 


EATING  FOR  HEALTH  AND  PLEASURE     65 


of  India,  of  South  America,  and  of  many  semi-civilized 
nations.  Among  savage  tribes,  one  meal  a  day  is  the 
prevailing  custom.  Though  the  Eskimo  hunter  sets 
out  fasting  in  his  Kajak  on  a  day's  hunt  at  break  of 
day,  he  eats  nothing  until  after  he  returns  from  his  perilous 
work  just  before  sunset.  The  ancient  Greeks,  Hebrews, 
and  Persians  ate  but  two  meals  a  day.  It  is  therefore 
evident  that  one  can  be  well  nourished  on  two  meals  a 
day.  In  modern  times  thousands  of  persons  have 
adopted  this  cus- 
tom with  benefit 
to  themselves. 

If  more  than  two 
meals  are  needed 
by  any  class,  it  is 
by  those  who  are 
engaged  in  severe 
muscular  labor. 
Such  persons  are 
better  able  to  di- 
gest a  third  meal 
than  those  whose 
work  is  mental  or 
sedentary,  as  we 
say.  If  a  third 
meal  is  taken  by  mental  workers,  it  should  be  very 
light.  All  that  has  been  said  about  too  frequent 
eating  shows  that  the  practice  of  eating  sweetmeats, 
confectionery,  nuts,  and  such  things  between  meals 


PERSONS  WHO  DO  HARD  MUSCULAR  WORK  MAY  EAT 
MORE  FREQUENTLY  THAN  THOSE  WHO  DO  NOT 
DO  HARD  WORK. 


66  THE   BODY  IN  HEALTH 

is  a  very  harmful  one.  It  is  a  certain  cause  of  in- 
digestion, for  no  stomach  can  long  endure  such  treat- 
ment. By  forming  this  bad  habit  in  childhood,  many 
persons  lay  the  foundation  for  much  suffering  from 
dyspepsia  later  in  life. 

Digestion  can  not  be  well  performed  during  sleep. 
A  sleeping  stomach  is  very  slow  in  its  work.  The 
Hindrances  gastric  juice  is  small  in  quantity  and  poor  in 
to  quality.  Bad  digestion  and  restless  sleep 

digestion.     are  the  result  of  jate  eat;ng      Through  the 

bad  habit  of  eating  just  before  retiring,  many  persons 
suffer  from  sleeplessness,  bad  dreams,  and  similar 
troubles  and  arise  in  the  morning  very  dull,  because 
the  work  of  nutrition  has  been  hindered. 

Usually  no  food  should  be  taken  within  four  hours 
before  retiring,  except  by  young  children.  This  will 
allow  time  for  the  stomach  to  finish  its  work  and  pass 
the  food  into  the  small  intestine.  Then  the  work  of 
digestion  may  be  completed  without  disturbance.  If 
any  food  at  all  is  taken  shortly  before  retiring,  it  should 
be  only  ripe  fruit,  or  fruit  juice,  which  does  not  require 
digestion,  but  is  ready  for  immediate  use. 

Another  cause  of  indigestion  which  is  closely  related 
to  those  we  have  studied,  is  irregularity  in  the  time 
of  meals.  Our  bodies  try  to  form  regular  habits. 
This  is  especially  true  with  respect  to  digestion.  If  a 
meal  is  taken  at  a  regular  hour,  the  stomach  will  be- 
come accustomed  to  receiving  food  at  that  hour  and 
will  be  prepared  for  it.  If  meals  are  eaten  irregularly, 


EATING   FOR   HEALTH  AND   PLEASURE      67 

the  stomach  does  not  know  what  to  expect.  It  is 
taken  by  surprise,  so  to  speak,  and  is  never  in  a  proper 
state  of  readiness  for  the  prompt  and  perfect  per- 
formance of  its  work.  You  must  remember  that  the 
action  of  the  digestive  organs,  like  that  of  all  the  other 
organs,  is  rhythmical,  —  that  is,  it  takes  place  at  regular 
intervals  or  periods.  It  is  far  better,  however,  to  omit 
a  meal  than  to  eat  when  not  hungry,  or  to  introduce 
into  the  stomach  a  new  supply  of  food  when  it  already 
contains  some  in  the  process  of  digestion,  or  before  it 
has  been  given  opportunity  to  rest. 

Violent  exercise,  either  just  before  or  just  after 
eating,  is  a  hindrance  to  digestion.  It  takes  the  blood 
away  from  the  stomach  to  other  parts  of  the  body,  and 
so  the  stomach  is  deprived  of  the  energy  needed  for 
good  digestion. 

For  the  same  reason  it  is  not  a  good  thing  to  eat 
when  one  is  very  tired.  The  energy  needed  for  the 
work  of  digestion  is  lacking  in  a  person  who  is  in  an 
exhausted  condition,  and  the  food  is  likely  to  remain 
in  the  stomach  for  some  time  undigested.  If  food  is 
needed  by  one  who  is  very  tired,  only  a  small  quantity 
of  an  easily  digested  kind  should  be  taken.  Nitrog- 
enous foods,  such  as  meat  and  eggs,  are  especially 
harmful  to  a  person  who  is  very  tired.  Thin,  well- 
boiled  gruel,  a  cup  of  vegetable  broth,  or  better  still,  a 
glass  of  fruit  juice,  are  best  for  tired  people.  Fruit 
juices  contain  food  ready  for  absorption. 

Not  only  should  one  not  eat  when  he  is  tired  ;   but 


68  THE   BODY  IN  HEALTH 

it  will  be  even  worse  if  he  eats  when  he  is  excited  or 
angry  or  irritated  in  any  way.  Why  ?  Professor  Paw- 
low  found  that  no  gastric  juice  was  formed 
digestion  m  tne  stomach  of  a  dog  if  the  animal  was 
isinflu-  annoyed  or  irritated  while  eating.  Some  ex- 
periments  made  by  Professor  Cannon  of 
Harvard  University  show  that  digestion  in 
the  small  intestine,  as  well  as  in  the  stomach,  is  greatly 
influenced  by  the  mental  state.  He  placed  a  cat  under 
the  X-ray,  so  that  he  could  see  the  stomach  and  the 
intestine.  The  cat  was  given  some  bread  and  milk 
containing  bismuth,  which  made  the  food  visible  under 
the  X-ray.  The  digestive  juices  began  to  flow ;  the 
stomach  and  intestines  began  their  muscular  work, 
and  everything  was  going  on  nicely,  and  the  cat  was 
purring  in  comfort  after  her  good  meal.  When  some- 
thing was  done  to  make  the  cat  nervous,  the  purring 
ceased,  and  all  the  digestive  work  began  to  slow  up. 
If  she  became  very  much  excited  or  angry  and  began 
to  spit,  the  digestive  juices  ceased  to  flow,  the  muscles 
stopped  work,  and  everything  was  at  a  standstill. 
The  work  of  digestion  stopped  entirely  until  pussy  was 
stroked  or  petted  into  a  good  humor.  This  shows 
us  that  the  happy,  peaceful,  satisfied  state  in  which 
a  cat  is  when  she  is  purring  is  the  most  helpful  to 
digestion. 

The  mind  should  be  in  a  cheerful  frame,  especially 
while  food  is  being  eaten  and  digested.  What  sort  of 
conversation  should  there  be  at  the  table  ?  Arguments 


EATING   FOR  HEALTH  AND   PLEASURE     69 

or    disagreements    and    everything   of   an    unpleasant 
nature  should  be  carefully  avoided. 

The  ancient  custom  of  having  a  jester  at  the  table 
to  make  people  laugh  while  eating  was  good  for  their 
health  as  well  as  their  humor.  "Laugh  and  grow 
fat  "  is  an  old  maxim. 

A  natural  and  healthy  appetite  is  the  best  guide  as  to 
how  much  one  should  eat.  If  one  eats  in  a  proper 
manner,  chewing  every  morsel  until  it  is  The 
liquid,  his  appetite  will  guide  him  in  the  normal 
selection  of  the  food  needed  and  will  recog-  gmde- 
nize  when  he  has  had  enough  of  protein,  starch,  fat, 
or  acid.  You  already  know  something  about  the 
remarkable  signaling  system  by  means  of  which  the 
digestive  work  is  controlled.  The  regulation  of  the 
appetite  is  an  interesting  part  of  this  system.  There 
are  in  the  brain  certain  centers  which  have  been  called 
"hunger  centers."  When  the  body  is  in  need  of  food, 
a  message  is  sent  up  to  these  hunger  centers  and,  from 
them,  transmitted  to  the  mouth  by  the  nerves  of  taste, 
creating  a  desire  for  food,  that  we  call  "appetite." 
When  enough  of  a  certain  kind  of  food  has  been  re- 
ceived into  the  body,  the  "hunger  centers  "  are  notified 
that  no  more  is  needed,  and  the  appetite  for  that 
particular  food  is  cut  off.  Pawlow's  dogs  continued 
eating  with  unabated  appetite  for  hours  at  a  time 
when  their  food  passed  into  a  dish  instead  of  into  the 
stomach.  Since  no  food  was  received  into  the  body,  no 
message  was  sent  up  to  the  brain  to  cut  off  the  supply, 


70  THE   BODY  IN  HEALTH 

When  one  bolts  his  food,  he  can  not  discover  when 
he  has  had  enough,  for  some  of  the  food  must  get 
into  the  blood  before  the  "hunger  center"  will  ring 
the  bell,  so  to  speak,  for  the  supply  to  cease.  When 
one  hurries  food  into  the  stomach,  he  gets  more  than 
he  needs  before  the  "hunger  center"  finds  it  out, 
and  he  stops  only  when  he  is  so  full  that  he  can  not 
take  any  more. 

We  can  now  see  how  some  of  the  bad  habits  that  we 
have  been  considering  —  eating  too  fast,  drinking 
Waste  in  too  much  at  meals,  and  taking  too  great  a 
eating.  variety  of  food  at  a  meal  —  lead  to  the 
further  bad  habit  of  eating  too  much.  The  digestive 
organs  are  then  overtaxed  to  take  care  of  a  quantity 
of  food  that  is  not  needed.  Not  only  is  there  this 
waste  of  energy  in  digestion,  but  all  food  taken  into 
the  body  beyond  what  is  needed  is  not  only  of  no  use 
but  it  is  actually  harmful.  If,  in  repairing  a  house, 
a  great  deal  more  material  than  is  needed  is  carried 
into  the  house,  it  is  only  in  the  way  of  the  workmen, 
and  they  have  to  spend  their  strength  in  carrying  it 
out.  It  is  just  so  with  the  little  cell  workers  of  the 
body.  When  more  food  is  taken  into  the  body  than 
is  needed  for  their  work,  it  becomes  simply  so  much 
rubbish  that  must  be  got  out  of  the  way  as  soon  as 
possible.  It  puts  an  extra  burden  upon  the  cells  to 
get  rid  of  it. 

The  sense  of  taste  was  given  to  us  to  be  our  guide 
in  supplying  the  needs  of  the  body  and  not  for  our 


EATING  FOR   HEALTH  AND   PLEASURE      71 

gratification  merely.  When  we  eat  things  that  are 
harmful  to  the  body  or  eat  too  much  even  of  what  is 
good,  because  it  pleases  our  taste,  we  are  injuring 
the  sense  of  taste,  so  that  it  will  no  longer  be  a  safe 
guide. 

If  we  know  how  to  eat,  and  we  do  that  in  a  proper 
manner,  we  know  just  how  much  to  eat,  the  appetite 
will  crave  the  right  kind  of  food  in  the  right  quantities, 
and  will  make  all  the  digestive  juices  needed  for  the 
digestion  of  the  food. 

HEALTH  PROBLEMS 

1 .  How  many  minutes  do  you  take  for  each  meal  ?     Do  you 
know  people  who  hurry  through  every  meal  as  if  they  had  to  catch 
a  train  ?     If  so,  are  they  healthy  and  successful  people  ? 

2.  Eat  a  slice  of  bread  by  chewing  it  until  it  swallows  itself. 
How  does  it  taste  ?     Explain. 

3.  Put  your  hand  into  a  bowl  of  ice  water;   how  long  can  you 
endure  it  ?     How  long  could  you  keep  your  face  in  it  ?     How  do 
you  think  one's  stomach  would  like  to  have  a  bowl  of  ice  water 
poured  into  it  ? 

4.  Do  you  know  people  who  have  got  in  the  habit  of  nibbling 
at  food  much  of  the  time  ?     Tell  about  such  a  person's  health  and 
his  good  feeling. 

5.  Look  up  the  meaning  of  dyspepsia.     Then  make  out  a  list 
of  the  eating  habits  one  should  form  in  order  to  avoid  this  disease. 

6.  How  would  it  do  for  one  to  get  into  the  habit  of  eating 
breakfast  one  day  at  8  o'clock,  the  next  day  at  10  o'clock,  the  next 
day  at  9  o'clock,  and  then  go  back  to  10  o'clock  and  repeat  the  pro- 
cess ?    Would  it  make  any  difference  if  this  irregularity  occurred  at 
dinner  or  supper  ? 


72  THE   BODY  IN  HEALTH 

7.  How  would  it  do  to  jump  up  from  the  table  at  dinner  and 
run  a  race  with  a  companion  ?     Explain. 

8.  If  people  must  quarrel,  what  time  should  they  avoid  doing 
it  ?     Explain.     What  of  telling  the  news  of  murders,  floods,  fires, 
and  scandals  at  the  table  ? 


REVIEW  QUESTIONS 

1.  What  has  Nature  done  to  induce  people  to  chew  food  thor- 
oughly ? 

2.  Should  food  be  attractive  to  the  eye  as  well  as  to  the  smell 
and  taste  ?     Why  ? 

3.  How  long  should  food  be  kept  in  the  mouth  ? 

4.  What  may  happen  in  the  stomach  if  food  is  not  thoroughly 
chewed  before  it  is  swallowed  ? 

5.  Why  do  people  so  often  bolt  their  food  ? 

6.  What  is  the  danger  in  eating  moist  foods  like  mushes  and 
soups  ?     If  one  eats  such  foods,  what  special  care  must  be  taken 
with  them  ? 

7.  How  do  farmers  treat  their  horses  to  prevent  them  from 
bolting  their  food  ? 

8.  What  is  often  the  cause  of  drinking  large  quantities  of 
liquids  at  meals  ?     What  is  the  harm  of  so  doing  ? 

9.  What   temperature   is   required  for  digestion  ?     How  will 
a  glass  of  ice  water  affect  this  temperature  ? 

10.  What  is  the  harm  of  drinking  very  hot  drinks   during 
meals  ? 

11.  If  one  must  drink  during  meals,  how  should  he  do  it  ? 

12.  Is  a  variety  of  food  at  a  meal  good  for  the  health  ?     Why  ? 

13.  Why  is  it  harmful  to  take  fresh  food  before  the  previous 
meal  has  been  digested  ? 

14.  How  many  meals  a  day  are  necessary  for  people  of  different 
ages  ? 


EATING  FOR  HEALTH  AND   PLEASURE      73 

15.  Is  there  any  harm  in  eating  just  before  going  to  bed  ?     If 
food  must  be  taken  just  before  bed  time,  what  should  it  be  ? 

1 6.  Is  there  any  harm  in  eating  at  irregular  times  ?     Why  ? 

17.  Is  there  any  harm  in  taking  violent  exercise  before  a  meal  ? 
Why  ?     What  of  eating  when  one  is  tired  ? 

1 8.  How  does  the  mind  influence  digestion  ? 

19.  What  are  the  hunger  centers  ? 

20.  How  can  we  tell  how  much  we  ought  to  eat  ? 

21.  What  habits  may  lead  one  to  eat  too  much  ? 

22.  How  may  one  injure  the  taste  so  that  it  may  not  be  a  safe 
guide  for  him  in  eating  ? 


CHAPTER  V 
THE  BLOOD 

MORE  than  a  century  ago,  a  great  English  scientist, 
John  Hunter,  performed  some  interesting  experiments. 
He  cut  all  the  nerve  trunks  that  supplied  the  limbs  of 
an  animal  and  then  watched  the  results.  The  limb 
was  paralyzed,  but  the  flesh  remained  warm,  the  cir- 
culation continued,  the  hair  and  nails  grew  as  before, 
and  so  the  limb  remained  alive.  The  muscles  shrank 
for  want  of  use,  but  otherwise  no  evidence  of  disease 
appeared.  An  experiment  was  then  made  in  another 
limb.  The  arteries  conveying  the  blood  to  the  part 
were  tied,  while  the  nerves  were  left  undisturbed. 
Note  the  different  result :  Within  a  few  hours  the 
limb  became  cold.  It  became  also  livid,  purple,  and 
finally  black.  Soon  the  flesh  began  to  fall  away. 
The  limb  had  died  and  had  become  simply  a  decaying 
mass.  These  experiments  clearly  showed  that  it  is 
the  blood  that  maintains  the  life  of  the  tissues  through 
which  it  flows.  The  blood  constantly  replaces  the 
worn-out  cells  and  fibers,  so  that  by  its  agency  the 
body  is  continually  renewed. 

The  eyes  with  which  we  look  out  upon  the  world 
to-day  are  not  composed  of  just  the  same  cells  as  those 
which  pictured  for  our  brain  the  happenings  of  the 
outer  world  a  year  or  two  ago.  The  muscles  which 

74 


THE  BLOOD  75 

move  us  about,  the  brain  and  nerves  with  which  we 
think  and  feel,  are  likewise  new.  All  the  soft  parts  of 
the  body  are  so  rapidly  changed  that  the  great  mass 
of  the  body  is  renewed  every  few  months  or,  at  the 
longest,  every  few  years.  It  is  by  means  of  the  blood 
that  this  body  rebuilding  is  constantly  carried  forward. 

The  blood  has  been  called  the  "carrier"  of  the  body. 
It  receives  the  digested  food  from  the  alimentary 
canal  and  the  oxygen  from  the  lungs  and  carries  them 
to  the  waiting  tissues  in  all  parts  of  the  body.  The 
tiniest  cell,  no  matter  how  far  removed  from  the  great 
centers  of  life,  receives  its  due  share  of  nutriment 
through  the  medium  of  the  blood.  The  blood  might 
well  be  called  a  "traveling  exchange,"  for  in  return 
for  the  new  material  which  it  supplies  to  the  tissues, 
it  carries  away  the  cell  wastes  to  the  organs  by  which 
they  are  expelled  from  the  body.  Is  this  constant 
exchange  of  matter  in  the  body  essential  to  life  ?  Why  ? 
Do  you  think  that  the  more  rapidly  old  material  is 
carried  away  and  new  material  deposited  in  its  place, 
the  more  rapidly  the  wheels  of  life  will  turn  and  the 
more  one  will  really  live  ? 

As  you  look  at  blood  it  appears  to  be  red,  but  when  you 
examine  it  under  the  microscope,  it  no  longer  The  blood 
looks  red.     It  is  then  seen  to  be  filled  with  cells,  red 
very  small  forms  known  as  the  blood  cells  andw^ie- 
or  corpuscles. 

The  number  of  these  cells  is  so  great  that  a  very  small 
drop  of  blood  contains  more  than  five  millions,  and  the 


76  THE   BODY  IN  HEALTH 

number  contained  in  the  body  of  an  average  man  is 
twenty-five  million  of  millions,  —  25,000,000,000,000. 
In  other  words,  a  man  has  in  his  body  twelve  thousand 
times  as  many  individual  blood  cells  as  there  are  people 
on  the  earth.  The  blood  cells  are  so  small  that  it 
takes  from  2500  to  3500  to  make  a  row  an  inch  long; 
but  their  number  is  so  great  that  the  blood  cells  of  a 

man  arranged  in  a  sin- 
gle row  would  reach  four 
times  around  the  earth. 
Each   of  these   little 
cells  is  a  distinct  living 
creature,  but  its  period 
of  life  is  only  about  six 
weeks.     Consider  for  a 
BLOOD  CELLS.  moment  the  significance 

I,  red  blood  cells;  2,  white  blood  cells.          Qf      tnjg          Twenty-five 

millions  of  million  blood  cells  must  be  created  every  six 
weeks.  This  requires  the  making  of  blood  cells  at  the 
rate  of  more  than  seven  millions  per  second.  At  every 
tick  of  the  clock,  seven  million  blood  cells  die,  on  the 
average ;  and  seven  million  more  must  be  created  to 
take  their  places.  Do  you  see  what  a  wonderful  fac- 
tory the  human  body  is  ? 

A  close  look  at  the  blood  cells  under  the  microscope 
will  show  that  they  are  of  various  shapes  and  sizes. 
The  smaller  ones  are  the  most  numerous.  They  have 
the  shape  of  flattened,  biconcave  (hollowing  in  on  both 
sides  at  the  center)  disks,  and  are  of  a  faint  amber 


THE   BLOOD  77 

color.  These  are  the  oxygen  carriers  of  the  blood. 
They  carry  from  the  lungs  to  the  tissues  the  life-giving 
oxygen  upon  which  every  function  of  the  body  depends. 
It  is  by  means  of  a  pigment  they  contain  called  hemo- 
globin, which  gives  to  the  blood  its  red  color,  that  the 
red  cells  are  enabled  to  carry  oxygen. 

The  time  occupied  by  the  passage  of  the  blood 
through  the  lungs  is  very  brief,  only  a  few  seconds,  and 
yet  this  is  sufficient  for  the  unloading  of  the  poisonous 
carbon  dioxide3  which  is  received  from  the  tissues,  and 
the  taking  on  of  a  fresh  load  of  oxygen.  The  lungs 
may  be  regarded  as  the  chimney  of  the  body,  —  the 
carbonic  acid  gas  is  the  smoke  ;  and  the  oxygen,  the  air 
which  comes  in  through  the  draught ;  thus  the  lungs 
serve  the  purpose  of  a  draught  as  well  as  that  of  a 
chimney.  Suppose  that  a  stove  were  constructed  with 
but  one  small  opening  for  the  entrance  of  air  and  the 
outlet  for  smoke.  The  fire  might  be  started  in  such 
a  stove,  but  it  would  quickly  be  smothered  by  the 
accumulation  of  smoke,  which  would  prevent  the  en- 
trance of  fresh  air.  The  same  thing  would  happen 
to  the  body  were  it  not  for  the  red  blood  cells.  These 
carry  in  the  fresh  air,  the  oxygen,  and  assist  in  carrying 
out  the  smoke,  just  as  men  might  carry  into  a  laundry 
buckets  of  pure  water  and  carry  out  the  dirty  water 
resulting  from  the  washing  process. 

The  white  blood  cells  show  many  different  sizes 
and  shapes.  In  the  resting  or  quiet  state,  the  white 
cells  are  transparent  spherical  forms,  resembling  jelly 


78  THE   BODY  IN  HEALTH 

drops,  which  float  in  the  blood  stream.  They  are 
able  to  move  like  the  amoeba  by  changing  their  form, 
-stretching  themselves  out  into  elongated  shapes 
and  gathering  themselves  together  again  like  a 
worm. 

The  red  cells  do  not  leave  the  blood  vessels,  but  the 
white  cells  have  the  power  to  pass  straight  through 
the  walls  of  the  capillaries,  which  are  small  blood 
vessels,  leaving  no  gap  or  opening  behind  them.  Just 
how  they  accomplish  this  is  one  of  the  mysteries  of 
science. 

The  white  cells  of  the  blood  have  been  well  called 
the  "Army  of  the  Interior,"  because  they  are  the  de- 
fenders of  the  body  against  disease  and  other  dangers. 
Every  human  body  is  guarded  and  defended  by  a 
countless  host  of  little  living  soldiers,  some  of  whom 
guard  the  walls  and  fortifications,  while  others  like 
"flying  columns"  move  about  freely  to  spy  out  the 
enemy  and  attack  him  at  whatever  point  he  appears. 
They  seem  to  have  no  generals  and  no  commander- 
in-chief,  yet  they  act  in  unity  and  harmony  that  might 
well  serve  as  a  model  to  the  great  armies  of  the  world. 
They  possess  powers  superior  to  the  most  experienced 
veteran  of  any  army.  They  never  sleep,  but  keep 
constant  watch  day  and  night  and  seem  to  detect  by 
instinct  the  approach  of  an  enemy.  They  are  able 
to  change  their  form  and  take  on  that  most  suitable 
for  their  object.  More  wonderful  still,  they  are  able 
to  penetrate  vessel  walls  and  other  tissues  without 


THE  BLOOD  79 

difficulty.  The  law  of  their  being  is  that  they  must 
conquer  or  die,  and  they  frequently  do  lay  down  their 
lives  in  great  numbers  to  save  the  body  which  it  is 
their  business  to  defend. 

Each  cell  seems  to  have  a  will  of  its  own  and  a 
peculiar  intelligence  by  which  it  is  unerringly  led  to 
the  place  where  it  is  needed.     Suppose,  for  Thedefen_ 
example,    a   few   germs   are   introduced    into  siveand 
some  transparent  tissue   (tissue   one  can  see  healing 
through),  such  as  the  web  of  a  frog's  foot  or  Ofthe 
the  wing  of  a  bat.     What  happens  may  be  blood 
noted  with  a  powerful  microscope.     Watch-  ceUs' 
ing  closely,  one  may  see  the  white  cells  beginning  to 
accumulate  on  the  wall  of  the  vessel,  just  opposite 
where  the  germs  have  entered.     The  cells  move  more 
and    more    slowly,    creeping    carefully    along,    as   one 
often  sees  a  dog  tracking  his  master  or  game  of  some 
sort.     By  and  by  the  moving  mass  of  cells  comes  to  a 
stop.     Then  each  cell  begins  to  push  out  a  tiny  thread 
of  its  own  tissue,  thrusting  it  through  the  wall  of  the 
vessel.     Little  by  little  the  farther  end  of  the  delicate 
filament    which   has   been    pushed    through   the   wall 
grows  larger  and  larger,  while  the  portion  within  the 
wall   gets   smaller.     After   a   little   time   each    cell   is 
found  outside  the  vessel,  yet  the  vessel  wall  remains 
as  perfect  as  before.     Apparently  each  cell  has  made  a 
minute  opening  and  has  then  tucked  itself  through, 
as  one  might  tuck  a  pocket  handkerchief  through  a 
ring. 


8o 


THE   BODY  IN  HEALTH 


Once  outside  the  blood  vessel,  the  body  defenders, 
moving  here  and  there,  quickly  discover  the  germs  and 
proceed  at  once  to  devour  them.  This  they  do  by 
enclosing  them  or  surrounding  them  with  their  own 
little  bodies.  If  the  germs  are  few,  they  may  soon  be 
destroyed  in  this  way,  for  the  white  cells  not  only 
swallow  germs  but.  digest  them.  If  the  number  is 
very  great,  however,  the  cells  sacrifice  themselves  in 
the  effort  to  destroy  the  germs,  taking  in  more  than 

they  are  able  to  digest 
and  destroy.  When  this 
occurs,  the  germs  con- 
tinue to  increase,  more 
white  cells  make  their 
way  out  of  the  blood 
vessels,  and  a  fierce  and 
often  long-continued  bat- 


BATTLE    BETWEEN   THE  WHITE  CELLS 
AND    INVADING    GERMS. 


g  wage  etWCCU    the 

-    •     .  ,      r  i  11 

body  defenders  and  the 
invading  germs.  The  white  cells  hasten  to  the  scene 
of  the  conflict,  from  all  parts  of  the  body,  until  the 
number  may  be  so  great  as  to  cause  a  swelling  of  the 
part  where  the  battle  is  in  progress.  It  is  in  this  way 
that  a  boil  or  an  abscess  is  formed,  and  the  "pus"  which 
is  discharged  consists  of  the  dead  white  cells  which 
have  laid  down  their  lives  in  defense  of  the  body. 
The  number  of  cells  which  may  be  sacrificed  in  such 
a  battle,  when  it  is  waged  day  by  day,  may  be  shown 
in  the  fact  that  a  single  ounce  of  pus  may  contain  as 


THE   BLOOD  81 

many  as  150,000,000  of  these  fighting  cells  which  have 
died  in  their  efforts  to  repel  the  invading  germs. 

When  any  part  of  the  body  is  injured,  white  cells 
accumulate  in  great  numbers.  They  spread  them- 
selves over  the  surface  of  the  wounded  parts  and 
dexterously  weave  a  new  fabric  to  cement  the  ends  of 
a  broken  bone  or  to  cover  a  surface  which  has  been 
made  bare.  In  the  formation  of  a  portion  of  the 
surface  from  which  the  skin  has  been  removed,  we 
see  the  creating,  healing  process  which  by  means  of 
the  blood  is  being  continually  carried  on  in  the  body. 

If  you  would  like  to  see  this  illustrated,  watch  the 
healing  of  a  cut.  The  blood  forms  a  clot  in  the  open- 
ing, and  if  you  examine  that  clot  through  a  microscope, 
you  will  find  a  perfect  network  of  little  strings  or  fibers, 
like  the  wire  used  in  the  building  of  a  bridge,  running 
from  one  side  of  the  cut  to  the  other.  Soon  you  will 
see  creeping  out  on  those  threads  some  white  blood 
cells,  which  begin  the  work  of  repair.  They  build 
up  the  blood  vessels  and  nerves  and  fill  up  the  space 
with  new  tissue  to  heal  the  cut. 

Some  of  the  white  cells,  called  phagocytes,  act  as 
scavengers,  going  through  the  body  and  gathering  up 
materials  that  are  no  longer  of  any  use  and  conveying 
them  to  places  where  they  may  be  got  rid  of.  There 
are  various  sorts  of  white  cells,  each  of  which  probably 
has  its  own  special  work  to  do ;  but  this  is  a  question 
concerning  which  very  little  is  known.  Do  you  not 
see  how  really  wonderful  this  body  of  ours  is  ? 


82  THE   BODY  IN   HEALTH 

The  fluid  portion  of  the  blood  in  which  the  cells 
float  is  called  plasma.  This  is  composed  chiefly  of 
water  in  which  the  digested  food  elements  are  dissolved. 
It  contains  also  gases  and  other  poisonous  products 
discharged  into  it  by  the  tissues.  It  is  necessary  for 
the  activity  of  the  blood  cells  and  the  tissues  that  the 
blood  should  be  in  an  alkaline  condition.  The  degree 
of  alkalinity  of  the  blood  changes  considerably.  The 
absorption  of  waste  substances  from  the  tissues  and 
of  the  acids  formed  by  fermentations  from  the  stomach 
and  intestines  lessens  this  alkalinity.  It  is  also  les- 
sened by  sedentary  habits ;  by  neglect  to  take  proper 
exercise  ;  by  impure  air  ;  by  the  use  of  alcohol ;  and 
by  various  diseases,  especially  rheumatism.  Certain 
articles  of  food,  especially  meat,  which  contains  uric 
acid,  may  lessen  the  alkalinity  of  the  blood.  .This  is 
a  matter  of  great  importance,  for  the  reason  that  the 
blood  serum,  like  the  white  cells,  when  in  a  state  of 
health  has  the  power  to  destroy  germs.  But  when 
its  alkalinity  is  lessened  by  the  causes  mentioned,  this 
power  is  to  a  large  extent  lost.  As  a  result,  the  power 
of  the  body  to  defend  itself  against  intruding  germs 
is  actually  destroyed.  This  is  one  of  the  reasons  why 
persons  suffering  from  indigestion  are  more  liable  to 
contract  typhoid  fever,  cholera,  and  other  germ  diseases 
than  are  those  who  have  sound  stomachs. 

We  have  seen  that  the  blood  is  the  carrier  for  the 
body,  and  therefore  it  must  be  kept  in  constant  motion. 
It  used  to  be  thought  that  the  blood  simply  moved 


THE   BLOOD  83 

back  and  forth  in  the  blood  vessels,  as  the  waters  of 
the  sea   ebb  and  flow.     But  in  1621   it  was  . 

j.  j     ,  T-      i-  i        i        •    •  i    The  heart 

discovered    by  an  English  physician,  named  and  the 
William    Harvey,  that    the  blood  circulates,  blood 
flowing  in  the  blood  vessels  like  a  stream, 
always  in  one  direction,  and  returning  to  its  source, 
or  starting  place. 

It  has  been  shown  by  experiments  upon  animals 
that  all  the  blood  in  the  body  passes  through  the 
various  organs  hundreds  of  times  in  the  course  of  a 
single  day.  By  what  wonderful  machinery  is  this  rapid 
and  constant  circulation  of  the  blood  accomplished  ? 

The  chief  power  which  causes  the  circulation  of  the 
blood  is  the  beat  of  the  heart.  Some  organs  of  the 
body  perform  several  different  kinds  of  work;  but 
the  heart  has  a  single  purpose,  —  that  of  keeping  the 
living  stream  of  life  always  flowing  through  the  body, 
bathing  every  cell  and  tissue,  feeding  every  organ, 
washing  away  waste  particles,  and  carrying  them  to 
the  outlets  of  the  body,  so  that  they  may  be  got  rid  of. 

The  heart  is  a  hollow  muscle  about  the  size  of  the 
fist,  situated  just  behind  and  to  the  left  of  the  upper 
and  middle  portion  of  the  breast  bone.  Its  shape  is 
conical.  As  it  contracts,  its  apex  taps  the  chest  wall 
at  a  point  just  below  the  fifth  rib,  where  its  movements 
can  be  felt  easily. 

The  heart  is  double ;  or,  rather,  there  are  two  hearts, 
a  right  heart  and  a  left  heart,  almost  identical  in 
form.  There  are  valves  in  the  heart,  very  similar  to 


84 


THE   BODY  IN  HEALTH 


those  in  a  pump,  so  arranged  that  when  the  heart 
contracts,  emptying  itself,  the  blood  forced  out  can  not 
return.  A  very  ingenious  check-valve  arrangement 


THE  HEART. 

The  Heart  with  its  arteries  and  veins,  i.  heart;  2.  pulmonary  artery;  3.  aorta ; 
4.  pulmonary  vein;  5.  vena  cava  superior;  6.  right  subclavian  artery;  7.  left 
subclavian  artery;  8.  and  9.  carot'd  arteries. 

relieves  the  heart  of  the  pressure  of  the  blood  which 
has  been  forced  out  of  it,  as  you  can  see  in  the  illus- 
tration. 

By  placing  the  ear  at  a  point  below  the  fifth  rib, 


THE   BLOOD  85 

about  two  inches  to  the  left  of  the  breast  bone,  where 
the  heart  movements  are  felt,  one  may  hear  two  dis- 
tinct sounds  made  every  time  the  heart  beats,  which 
closely  resemble  the  syllables,  "  lub-dup."  These  sounds 
are  produced  by  the  movement  of  the  heart  and 
the  closure  of  its  valves,  and  are  like  the  thumping 
and  clicking  sounds  which  accompany  the  action  of 
a  water  pump. 


CHECK  VALVES  IN  THE  HEART. 

The  organs  used  in  the  circulation  of  the  blood  are 
not  confined  to  the  chest,  but  they  extend  throughout 
the  whole  body.  They  consist  of  the  central  part, 
the  heart,  and  two  sets  of  branching  tubes  connected 
with  it.  One  of  these  sets  of  tubes  starts  at  the  right 
heart,  the  other  at  the  left  heart.  The  system  which 
begins  at  the  left  heart  extends  throughout  the  body, 
ending  at  the  right  heart ;  the  one  which  begins  at  the 
right  heart  is  distributed  to  the  lungs  only  and  ends 
at  the  left  heart,  as  shown  in  the  picture. 


86 


THE  BODY  IN  HEALTH 


CIRCULATION  OF  THE  BLOOD. 

i.  aorta;    2.  subclavian  vein;    3.  descending  vena  cava;   4.  ascending  vena 
cava;  5.  subclavian  artery;  6.  descending  aorta. 


THE  BLOOD  87 

In  each  set  of  tubes  there  is  a  main  tube  starting 
out  from  the  heart,  dividing  into  many  branches, 
which,  after  becoming  very  small,  combine  to  form 
larger  ones,  finally  making  large  trunks,  which  again 
join  the  heart.  The  tubes  leading  out  from  the  heart 
are  called  arteries  ;  those  which  lead  back  to  the  heart 
are  called  veins.  The  minute  vessels  which  join  the 
arteries  and  the  veins  are  called  capillaries. 


THE    PASSAGE    OF  THE    BLOOD    FROM    ARTERY   TO   VEIN. 

I,  artery;  2,  capillaries;  3,  vein. 

The  walls  of  the  arteries,  and  to  some  extent  also 
the  walls  of  the  veins,  are  muscular  and  hence  are 
able  to  contract.  The  walls  of  the  arteries  and  veins 
are  thick  and  strong;  the  walls  of  the  capillaries, 
however,  are  extremely  thin,  far  more  delicate  than 
the  finest  gossamer  silk.  They  are  transparent,  so 
that  by  placing  under  a  microscope  a  bit  of  thin  tissue, 


88  THE   BODY  IN  HEALTH 

like  the  web  of  the  foot  of  a  living  frog,  one  may  easily 
see  the  blood  moving  through  these  minute  vessels 
and  study  their  rhythmical  contractions.  The  con- 
tractions of  the  heart  may  also  be  studied,  either  by 
placing  under  a  microscope  some  minute  living  crea- 
ture, as  a  very  young  minnow,  or  some  still  smaller 
animal  form,  such  as  the  minute  animalculae  which 
are  often  seen  swimming  around  in  stagnant  water. 
By  means  of  the  X-rays  it  is  also  possible  to  study  the 
movements  of  the  human  heart. 

(i)  The  left  heart  works  to  supply  the  body  with 
blood  for  the  building  up  of  its  tissues.  The  right 
The  three  heart  works  for  the  purpose  of  pumping  to 
systems  of  the  lungs  for  purification  the  blood  which 
circulation.  jias  gathered  up  the  poisonous  wastes  from 
the  tissues.  The  blood  that  goes  from  the  left  side  of 
the  heart  through  the  arteries  is  returned  through  the 
veins  to  the  right  side.  It  is  then  pumped  to  the 
lungs  by  the  right  heart,  and,  after  purification,  it  is 
returned  from  the  lungs  to  the  left  heart. 

The  blood  thus  passes  through  two  circuits :  the 
larger  of  which,  starting  with  the  left  side  of  the  heart 
and  ending  with  the  right  side,  is  termed  the  systemic 
circulation ;  the  smaller,  starting  out  from  the  right 
heart  and  ending  with  the  left  heart,  is  called  the 
pulmonary,  or  lesser,  circulation. 

Each  heart  is  divided  into  two  compartments,  one 
which  receives  the  blood  and  one  which  sends  it  out. 
The  receiving  compartment  is  called  the  auricle,  from 


THE   BLOOD  89 

its  fancied  resemblance  to  an  ear;    the  compartment 
which  forces  out  the  blood  is  called  the  ventricle. 

A  volume  of  blood  equal  to  the  total  amount  con- 
tained in  the  body  passes  through  each  side  of  the 
heart  about  once  every  minute.  Some  portions  of  the 
blood,  however,  complete  the  circuit  in  about  half 
this  time.  The  blood  travels  in  the  arteries  very 
rapidly,  but  in  the  capillaries  the  blood  movements  are 
so  slow  as  to  be  almost  unnoticeable.  The  length  of 
the  capillaries,  however,  is  so  very  short  that  the  time 
occupied  in  passing  through  them  is  brief.  It  has  been 
calculated  that  the  capillaries  can  hold  several  times 
as  much  blood  as  the  arteries.  This  partly  accounts 
for  the  slow  movement  of  the  blood  in  the  capillaries. 

The  network  of  capillaries  in  the  skin  is  spread  out 
over  an  area  of  more  than  ten  thousand  square  feet. 
Those  of  the  rest  of  the  body  must  be  sufficient  to  cover 
many  times  this  surface. 

The  blood  travels  much  more  slowly  in  the  veins 
than  in  the  arteries.  Its  force  is  also  very  much  less, 
a  condition  which  accounts  for  the  fact  that  when  an 
artery  is  cut  the  blood  spurts  out  with  considerable 
force  and  in  jets  corresponding  with  the  beats  of  the 
heart ;  whereas  the  flow  of  blood  from  a  cut  vein  is 
in  a  steady  stream  with  very  little  force.  The  veins 
differ  from  the  arteries  in  that  they  are  supplied  at 
various  points  with  check  valves,  which  prevent  a  back- 
ward movement  of  the  blood,  as  shown  in  the  illus- 
tration. 


9o 


THE   BODY  IN  HEALTH 


(2)  The  pulmonary  or  lung  circulation  starts,  as  we 

have  found,  from  the  right  heart 
and  pumps  it  into  the  lungs  for  puri- 
fication. In  the  lungs,  the  blood  is 
spread  out  in  a  fine  capillary  network, 
distributed  in  the  membrane  lining 
the  air  passages  and  air  cells,  which 
extend  over  an  area  which  has  been 
calculated  to  be  about  two  thou- 
sand square  feet.  After  passing 
through  the  lungs,  the  blood  is  re- 
turned to  the  left  heart  to  be  sent 
throughout  the  body  again.  So  it 
goes  on  hour  after  hour,  day  after 
day,  and  year  after  year,  as  long  as 
one  lives. 

(3)  The  portal  circulation  is  a  remarkably  interest- 
ing arrangement  of  blood 

vessels  connected  with  the 
digestive  organs  and  the 
liver.  The  blood  which  is 
supplied  to  the  stomach 
and  intestines  and  other 
organs  connected  with  the 
work  of  digestion,  on 
entering  the  veins  does 
not  return  at  once  to  the 
right  heart  as  does  the 
blood  from  other  parts  of  the  body,  but  is  carried  to 


CHECK  VALVES  IN  THE 
VEINS. 


THE  LUNGS. 


THE   BLOOD 


the  liver,  in  which  it  is  again  distributed  through 
a  set  of  capillaries  so  that  it  may  be  brought  in  con- 
tact with  the  living  cells  of  the  liver.  The  liver  cells 
are  thus  afforded  an  opportunity  to  remove  impu- 
rities that  may  have  been  absorbed  during  the 
process  of  digestion  and  also  to 
act  upon  the  several  elements  of 
the  food.  In  this  manner  it 
stores  up  the  sugar  from  the 
digested  starch  in  the  form  of 
glycogen  and  produces  some 
needed  changes  in  the  digested 
protein. 

The  thin  walls  of  the  capil- 
laries permit  the  escape  of  a 
considerable  quantity  of  the 
blood  into  the  tissues.  In  other 
words,  there  is  a  constant  leak- 
age from  the  blood  vessels.  This 
escaped  blood  is  called  lymph. 

The  lymph  is  the  means  of 
communication,  or  "middle- 
man/' as  it  has  been  called,  be- 
tween the  cells  and  the  blood. 
All  the  cells  of  the  body  are  bathed  in  lymph.  They  live 
in  lymph  just  as  a  fish  lives  in  water  or  as  the  body  as 
a  whole  lives  in  the  air.  They  take  up  from  the  lymph 
the  nourishing  substances  which  escape  into  it  from 
the  blood,  and  discharge  into  it  their  waste  substances. 


LYMPHATIC  GLAND. 


THE   BODY  IN  HEALTH 


The  pressure  within  the  blood  vessels  prevents  a  re- 
turn of  the  lymph  into  the  circulation.  Consequently, 
particular  provision  is  made  for  the  gathering  up  of 
these  escaped  blood  elements  in  a  special  set  of  ves- 
sels called  the  lymphatic  system.  There  are  located 

along  the  vessels 
at  certain  points 
small  bodies  called 
lymphatic  glands. 
The  vessels  do  not 
pass  through  these 
glands,  but  empty 
themselves  into 
the  glands  which 
are  drained  by 

VCSSCls    On     tllC    OD~ 
,  .   ,  r™ 

posite    side.     Ine 

r  •     •       i 

lymph  is  therefore 
passed  along  from  one  to  another  of  a  series  of  glands, 
until  it  finally  reaches  a  point  in  the  center  of  the 
body  near  the  heart,  where  the  various  lymphatic  ves- 
sels converge  and  discharge  their  contents  into  large 
veins. 

Germs  which  enter  the  body  through  the  skin  and 
find  their  way  into  the  lymphatics  can  not  reach  the 

The  battle     Deeper    anc^    Vital    Parts    °f   tne    body   without 

in  the          running  a  gantlet  of  many  lymphatic  glands, 
lymph         which  act  as  filters,  detaining  the  germs  and 
giving  the  white  cells  of  the   blood,   which 


THE  LYMPH  IS  THE  "  MIDDLEMAN  "  BETWEEN  THE 
CELLS   AND   THE    BLOOD. 

,.  ,      , 

I,  white  corpuscle;  2,  lymph. 


glands. 


THE   BLOOD  93 

are  always  present  in  these  parts  in  great  numbers, 
an  opportunity  to  destroy  them.  The  lymphatic 
glands  are  placed  in  great  numbers  in  those  parts 
of  the  body  where  germs  are  likely  to  enter.  It  is 
for  this  reason  that  they  are  so  numerous  about  the 
neck. 

Having   studied   the   several   routes   by  which   the 
blood  travels  in  the  body,  we  may  next  notice  how  it 
is  made  to  travel  along  these  channels.     The  How  the 
impulse  is  given  to  the  blood  movement  by  the  blood  is 
heart,  which  contracts  with  sufficient  force  to  circulated- 
elevate  the  blood  to  a  height  of  several  feet  in  a  tube 
connected  with  a  main  artery.     Perhaps  you  can  appre- 
ciate that  the  total  amount  of  work  done  by  the  heart 
in  twenty-four  hours  in  its  contractions,  in  an  average 
man,  is  equivalent  to  lifting  one  hundred  and  twenty- 
four  tons  one  foot   high,  or  lifting  a  hundredweight 
one  foot  high  2480  times,  or  at  the  rate  of  four  times  a 
minute  for  ten  hours. 

Even  the  expenditure  of  this  amount  of  energy  is 
not  sufficient  to  maintain  the  movement  of  the  blood 
current.  Other  forces  are  brought  into  operation 
which  greatly  assist  this  important  work.  The  cir- 
culation is  aided  by  the  rhythmical  contractions  of 
the  small  arteries  and  capillaries,  which  force  the 
blood  onward  in  a  steady  stream  into  the  veins. 
The  movements  of  the  body  produced  by  contrac- 
tions of  the  large  muscles  of  the  limbs  and  trunk 
aid  the  circulation  by  compressing  the  veins  and 


94  THE   BODY   IN  HEALTH 

thus  forcing  the  blood  forward ;  a  return  flow  is 
prevented  by  the  valves  of  the  veins.  The  breathing 
movements,  as  we  shall  see  later,  produce  a  sort  of 
suction  action  in  the  chest  which  draws  the  blood  to- 
ward the  heart. 

The  beating  of  the  pulse  goes  steadily  on  from  birth 
to  death  without  any  interruption.  How  is  this 
possible,  since  the  heart  is  a  muscle  and  the  muscles 
require  rest  ?  An  explanation  is  to  be  found  in  the 
fact  that  the  heart  takes  a  short  rest  at  the  end  of 
every  beat.  A  careful  study  of  its  action  shows  that 
it  spends  nearly  half  its  time  resting. 

The  rate  at  which  the  heart  works  varies  with  many 
conditions.  On  counting  the  pulse  at  the  wrist,  the 
ordinary  rate  in  an  adult  sitting  upright  is  found  to 
be  68.  In  the  same  person  lying  down  the  pulse  rate 
will  be  found  to  be  64  beats,  and  in  the  person  stand- 
ing the  rate  will  be  increased  to  78.  Why  this 
change  ?  Walking  at  a  moderate  rate  usually  raises 
the  pulse  to  about  100,  and  by  running  and  other 
violent  exercise,  it  may  be  increased  to  180  or  even 
more.  Why?  The  pulse  rate  of  an  infant  is  130  to 
140;  that  of  a  child  of  ten  years,  90.  In  aged  per- 
sons the  pulse  rate  is  found  to  be  from  five  to  ten 
beats  faster  than  in  middle  age.  In  fever  the  pulse 
rate  is  increased  one  fourth  or  more  and  is  sometimes 
even  doubled. 

The  blood  supply  of  the  body  in  general  is  regulated 
by  the  heart ;  but  each  particular  part  also  requires 


THE   BLOOD  95 

some  regulation  of  the  quantity  of  blood  supplied  to  it. 
This  is  effected  by  means  of  nerves  similar  to  those  which 
control  the  action  of  the  heart.     Through  the  Howthe 
influence  of  these  nerves,  the  muscular  walls  blood 
of  the  blood  vessels  are  made  to  contract  or  ^PP^  is 

1-1  1.  TT  ui       j    controlled. 

dilate  as   may  be  necessary.     It   more  blood 

is    required,    the    vessels    dilate,    thus    widening    the 

channel  and  increasing  the  supply. 

If  less  blood  is  needed,  the  vessels  contract,  thus 
diminishing  the  size  of  the  channel  through  which  the 
blood  must  flow.  These  nerves  are  brought  into 
action  when  cold,  heat,  friction,  or  other  irritants  are 
applied  to  the  skin. 

Cold  causes  contraction  of  the  vessel  walls ;  and 
heat,  friction,  or  other  irritants  dilate  them.  The 
contraction  from  the  effect  of  the  cold,  however,  is 
quickly  followed  by  a  dilatation,  or  so-called  reaction. 
The  dilatation  produced  by  cold  differs  from  that 
caused  by  heat,  in  that  it  is  more  permanent  and  is 
accompanied  by  an  active  movement  of  the  arteries, 
whereby  the  increased  amount  of  blood  is  pumped 
through  the  dilated  vessels.  Heat  apparently  dilates 
the  veins  more  than  the  arteries  and  does  not  increase 
the  activity  of  the  blood  current  through  the  skin.  It 
is  for  this  reason  that  heat  gives  to  the  skin  a  dusky 
red  hue,  while  the  reaction  produced  by  a  short  appli- 
cation of  cold  produces  a  crimson  red  color.  Pro- 
longed cold  produces  a  bluish  color,  by  so  contract- 
ing the  small  vessels  that  the  movement  of  the 


96  THE   BODY   IN   HEALTH 

blood  through  the  skin  is  almost  entirely  prevented 
The  little  blood  that  remains  in  the  veins  becomes  so 
thoroughly  charged  with  carbonic  acid  gas  that  it  ac- 
quires a  deep  blue  color,  which  gives  the  blue  color 
to  the  skin. 

HEALTH  PROBLEMS 

1.  For   purposes   of  experiment   tie  a   string   tightly  around 
your   finger   and   leave   it    there   for   a   few   minutes.     Describe 
what  happens  to  the  extremity  of  the  finger.     Suppose  the  string 
should    be  left  there   permanently;   what  would   happen  to  the 
finger  ? 

2.  If  you  think  it  is  appropriate  to  give  them  this  term,  show 
why  it  is  proper  to  speak  of  the  white  blood  cells  as  the  "Army 
of  the  Interior." 

3 .  Mention  some  of  the  common  enemies  of  the  body  that  would 
destroy  it,  if  the  white  blood  cells  were  not  always  on  guard  and 
in  good  fighting  condition. 

4.  Have  you  ever  been  in  a  condition  in  which  germ  enemies 
got  the  better  of  you  for  a  time  ?     Can  you  explain  this  ? 

5.  Think  of  some  sort  of  experiment  by  which  you  can  show  that 
a  large  proportion  of  the  body  is  water. 

6.  What   is   the   meaning   of  sedentary?     Mention  sedentary 
habits  of  people  whom  you  know.     What  do  such  people  need  to 
do  in  order  to  keep  in  good  health  ? 

7.  Physicians  tell  us  to-day  that  we  must  be  careful  not  to  eat 
too  much  meat.     Why  do  they  give  us  this  advice  ? 

8.  Mention  some  things  that  are  alkaline.     How  can  you  tell 
whether  a  thing  is  alkaline  or  not  ? 

9.  Locate  your  heart  precisely.     Point  out  exactly  where  it 
"taps  the  ribs." 

10 .  Suppose   the    valves    of   the    right  heart  should  become 


THE  BLOOD  97 

weakened,  what  would  happen  to  the  body  ?  Suppose  the  valves 
in  the  left  heart  should  become  weakened,  what  would 
happen  ? 

11.  Can  you  illustrate  the  arteries,  veins,  and  capillaries  in 
your  body  by  comparison   with   the  streets  of  your  city  ?     Are 
there  any  that  you  might  call  arteries,  others  capillaries,  and  others 
veins  ?     Why  ?     Can  you  speak  of  arteries,  capillaries,  and  veins 
in  a  plant  or  a  tree  ?     Why  ? 

12.  Why  are  the  capillaries  so  fine?     Why  should  not  they  be 
as  large  as  veins  ? 

1 3 .  Does  the  heart  work  harder  in  a  man  seven  feet  tall  than  one 
four  feet  tall  ?     Explain. 

14.  Why  does  the  heart  work  faster  when  one  is  climbing 
stairs  or  running  than  when  he  is  standing  still  or  sitting  down  ? 

15.  Show  the  checks  in  your  own  veins.     Which  way  should 
you    have  to   push   the   blood   in   order  to   show  these   veins  ? 
Why  ? 

1 6.  When  one's  feet  are  cold  or  when  he  has  a  headache,  why 
does  he  take  a  hot  foot  bath  ?     Why  does  he  put  on  cold  water 
after  he  has  had  a  hot  bath  ? 

17.  Write  a  story  entitled :    "The  Traveling  Exchange"  and 
show  all  the  good  which  can  be  performed  by  the  blood. 

REVIEW  QUESTIONS 

1.  What  is  it  that  maintains  the  life  of  the  tissues  of  the  body  ? 

2.  Are  the  cells  that  compose  any  organ  constantly  changing  ? 
How  do  we  know  ? 

3.  What  is  the  carrier  of  the  body  ?     What  does  it  carry,  and 
where  does  it  carry  it  ? 

4.  What  should  you  see  in  the  blood  if  you  should  examine  it 
under  a  microscope  ? 

5.  What  is  the  meaning  of  corpuscle  ? 

6.  How  many  blood  cells  in  a  drop  of  blood  ? 


98  THE   BODY  IN  HEALTH 

7.  If  all  the  blood  cells  in  the  body  were  put  together  in  a  row 
how  long  a  line  would  they  make  ? 

8.  How  rapidly  are  blood  cells  made  in  the  body  ? 

9.  How  do  the  red  blood  cells  look  under  a  microscope  ?    What 
is  their  office  ? 

10.  How  do  the  white  blood  cells  look  under  the  microscope  ? 
What  is  another  name  for  the  white  blood  cells  ?     What  is  their 
office  ? 

11.  Suppose  there  are  not  enough  white  blood  cells  in  the  body 
when  it  is  attacked  by  germs,  what  may  happen  ? 

12.  How  is  a  boil,  an  abscess,  or  pus  formed  ? 

13.  How  does  the  blood  heal  wounds  ? 

14.  Describe  the  work  of  the  plasma. 

15.  What  is  the  meaning  of  the  circulation  of  the  blood  and 
the  cause  of  it  ? 

1 6.  How  many  times  does  the  blood  in  the  body  pass  through 
the  different  organs  ? 

17.  Describe  the  heart,  telling  about  its  shape,  its  parts,  and 
its  work. 

1 8.  What  is  the  meaning  of  the  blood  vessels  ? 

19.  What  are  the  differences  among  an  artery,  a  vein,  and  a 
capillary  ? 

20.  What  is  the  systemic  circulation  ?    The  pulmonary  ? 

21.  Why  does  the  blood  travel  more  slowly  in  the  veins  than  in 
the  arteries  ? 

22.  How  has  Nature  arranged  it  so  that  the  blood  in  the  veins 
cannot  flow  back  into  the  arteries  ? 

23.  Why  is  all  the  blood  sent  to  the  lungs  ? 

24.  Why  is  some  of  the  blood  sent  to  the  liver  ? 

25.  What  is  the  lymphatic  circulation  ? 

26.  What  are  the  lymphatic  glands  ?     What  is  their  use  in  the 
body  ?     What  is  the  necessity  for  these  glands  ? 

27.  What  helps  the  heart  to  circulate  the  blood  ? 


THE   BLOOD  99 

28.  How  frequently  does  the  pulse  beat  in  an  average  adult 
(a)  when  he  is  sitting  upright,  (b)  when  he  is  standing,  (c).when  he  is 
walking,  (d)  when  he  is  running  rapidly  ? 

29.  How  is  the  blood  supply  to  any  organ  controlled  so  that  it 
will  get  just  the  amount  it  needs  ? 

30.  What  is  the  effect  of  cold  upon  the  circulation  in  any  of  the 
blood  vessels  ?    Of  heat  upon  the  circulation  ?     Why  does  cold 
produce  a  bluish  color  in  the  skin,  and  heat,  a  dusky  red  hue  ? 


CHAPTER  VI 
PURE  BLOOD  AND  A  SOUND  HEART 

THE  life  of  the  body  depends,  as  we  have  seen,  upon 
the  blood.  The  condition  of  the  blood  is  therefore  a 
The  im  matter  of  the  greatest  importance.  Upon  its 
portance  of  purity  depend  not  only  the  nutrition  of  the  body 
Wood  but  ^e  power  of  the  body  to  resist  diseases  of 
all  kinds.  Impure  blood  is  the  cause  of  a  large 
proportion  of  the  diseases  from  which  human  beings 
suffer. 

The  prompt  healing  of  a  cut  or  wound  is  evidence 
of  clean,  pure  blood.  When  the  skin  is  broken,  germs 
are  admitted  to  the  tissues,  from  which  they  are  ordi- 
narily kept  out  by  the  skin.  If  the  tissues  are  kept  in 
a  healthy  state  by  pure  and  vigorous  blood,  the  few 
germs  that  enter  are  quickly  destroyed,  and  there  is 
no  pus  ;  but  when  the  blood  is  not  pure,  the  cells  and 
the  blood  serum  are  not  able  to  make  the  active  defense 
necessary.  So  the  germs  multiply,  suppuration  (mak- 
ing of  pus)  occurs,  and  the  wound  may  take  a  long 
time  to  heal.  It  is  thus  clear  that  one's  blood  cells 
should  be  kept  in  good  fighting  condition,  so  they  may 
have  the  power  to  resist  and  destroy  germs.  We  owe 

100 


PURE   BLOOD  AND  A  SOUND  REART;  ; 

our  protection  or  recovery  from  infectious  diseases  of 
all  sorts  chiefly  to  the  activity  of  these  wonderful 
little  fighters. 

It  has  been  said  that  "all  life  is  under  water."  The 
cells  of  the  body  are  bathed  in  the  lymph  which  drains 
out  from  the  blood  vessels.  If  the  blood  is  impure, 
every  cell  and  fiber  of  the  body  is  bathed  by  an  im- 
pure fluid,  and  must  be  more  or  less  injured. 

Picture  in  your  mind  a  glass  globe  filled  with  water, 
with  fishes  swimming  about  in  it.  Imagine  that 
indigo,  ink,  or  some  other  kind  of  coloring  matter  is 
dropped  into  the  water.  All  the  water  will  at  once 
become  tinged,  and,  if  the  coloring  matter  is  poisonous, 
the  fishes  will  soon  show  signs  of  uneasiness  ;  and  un- 
less they  are  relieved  by  the  water's  being  changed, 
they  will  soon  die.  This  illustrates  the  condition  of 
the  living  cells  of  the  body  bathed  in  impure  blood. 
Every  one  is  injured  by  the  impurities  brought  in 
contact  with  it. 

You  see  now  why,  as  you  have  already  learned, 
all  substances  containing  poisons,  such  as  alcoholic 
drinks,  and  drugs  such  as  opium  and  tobacco,  in- 
jure the  blood  and  lessen  its  defensive  power.  When 
alcohol  is  taken  freely,  the  blood  loses  in  part  its  power 
to  carry  oxygen.  This  accounts  for  the  bluish  appear- 
ance of  the  face,  nose,  and  lips  of  an  "alcoholic,"  or 
one  who  drinks  a  good  deal  of  whisky,  beer,  or  the  like. 
Irritating  substances  such  as  pepper  and  mustard  are 
also  injurious  to  the  blood. 


102  IKE   BODY   IN  HEALTH 

Eating  too  much  will  render  the  blood  impure  by 
rilling  it  with  unused  materials,  which  must  be  treated 
as  waste  matter. 

Overwork  and  lack  of  sleep  render  the  blood  impure 
because  the  body  is  then  not  able  to  get  rid  of  the 
waste  tissues  or  poisons  which  form  in  large  quantities 
when  the  body  is  at  work.  The  work  of  repair  in  the 
body  is  more  active  during  sleep  than  during  waking 
time.  The  red  cells  of  the  blood  which  are  worn  out 
are  replaced,  and  thus  the  red  color  of  the  blood  is 
maintained.  If  one  does  not  sleep,  this  repair  of  the 
blood  does  not  take  place  so  perfectly. 

Neglect  to  maintain  the  right  activity  of  the  organs 
that  get  rid  of  wastes  —  the  lungs,  the  kidneys,  and 
the  bowels  —  allows  these  waste  matters  to  accumu- 
late in  the  blood,  and  they  spoil  it.  If  the  lungs  are 
not  rendered  active  by  proper  exercise,  the  blood  will 
not  get  a  sufficient  amount  of  oxygen  to  burn  up  the 
wastes,  and  they  will  get  into  the  skin  and  other 
tissues,  and  will  produce  a  dull,  muddy  complexion 
and  other  signs  of  impurity  of  the  blood. 

When  the  bowels  do  not  act  regularly  —  become 
constipated  —  the  poisonous  matters  which  are  re- 
tained are  absorbed  into  the  blood,  and  they  may  be- 
come a  source  of  disturbance  and  injury  throughout 
the  body.  If  a  sufficient  amount  of  water  is  not  taken 
to  dilute  the  blood,  wash  the  tissues,  and  assist  the 
kidneys  in  removing  the  acid  poisons  which  it  is  their 
particular  duty  to  separate  from  the  blood,  these  in- 


PURE   BLOOD  AND  A  SOUND   HEART      103 

jurious  substances  are  retained  and  give  rise  to  head- 
ache, rheumatism,  gout,  and  other  maladies. 

The  idea  that  the  blood  may  be  purified  by  medicine 
of  any  sort  is  a  great  error,  which  has  been  the  cause 
of  much  mischief.     There  are  no  herbs  nor  How  to 
drugs,   the   taking   of  which  will   purify  the  purify  the 
blood.     The  blood  is  not  purified  by  putting  bl°0(L 
something  into  it  but  by  taking  something  out  of  it. 
Water  is  the  universal  cleansing  agent,  and  its  free  use 
is    necessary    for    blood    purification.     It    washes    the 
tissues,  dilutes  the  blood,  and  encourages  the  kidneys 
to    remove    wastes.      To    undertake    to    purify    the 
blood   by   means   of  pills   is   about   as   reasonable   as 
to    undertake    to    cleanse    a    soiled   garment    by   the 
same  means. 

Vigorous  exercise  out  of  doors  is  one  of  the  most 
important  means  of  maintaining  blood  purity.  Why  ? 

An  insufficient  amount  of  food  very  soon  makes 
the  blood  poor  and  thin.  Of  course,  the  blood  must 
be  enriched  by  an  ample  supply  of  pure  foods,  as  well 
as  kept  pure  by  the  removal  of  wastes  and  the  keep- 
ing out  of  unwholesome  materials. 

Cold  baths  increase  the  number  of  active  cells  in 
the  blood.  Why,  do  you  think  ?  This  has  been  proved 
by  actually  counting  the  number  of  cells  before  and 
after  a  bath.  It  must  not  be  supposed  that  the  cells 
added  to  the  blood  are  formed  in  this  short  time. 
Cells  which  have  been  held  idle  are  by  this  means 
brought  into  the  active  circulation  and  made  useful. 


io4  THE   BODY  IN   HEALTH 

If,  however,  the  cold  bath  is  taken  regularly  from  day 
to  day,  there  is  an  actual  increase  in  the  number  of 
blood  cells  formed.  In  this  way,  the  cold  bath  in- 
creases the  resisting  power  of  the  body  and  rallies  the 
blood  cells,  so  to  speak,  calling  them  out  from  their 
hiding  places  and  preparing  them  to  fight  with  vigor 
the  battles  that  must  be  waged  every  moment  in  de- 
fense of  the  body.  Cold  baths  also  improve  the  quality 
of  the  blood  by  increasing  its  alkalinity.  The  circu- 
lation of  the  blood  is  quickened  and  improved  by  the 
cold  bath.  It  increases  the  force  of  the  heart  beat, 
and  deepens  the  breathing,,  so  that  an  increased  amount 
of  oxygen  is  taken  into  the  lungs  for  the  purification  of 
the  blood.  But  it  should  be  remembered  that  one 
must  always  react  to  cold  baths  or  they  may  injure 
him.  That  is,  he  must  feel  warm  and  vigorous  after 
them.  Most  people  cannot  remain  in  cold  water  for 
a  long  period  ;  they  may  become  chilled  and  seriously 
injured  if  they  try  it. 

In  order  that  the  blood  may  perform  its  work,  it  is 

necessary  not  only  that  it  should  be  rich  in 
thattffect  f°°d  elements  and  free  from  impure  substances, 
the  heart  but  it  must  also  be  circulated  properly  by  a 

strong  heart. 

Nature  has  provided  for  suiting  the  action 
of  the  heart  to  all  the  ordinary  needs  of  life ;  and  if 
we  are  careful  not  to  impose  needless  burdens  upon  it, 
nor  to  illtreat  it  in  any  way,  we  may  expect  it  to  do 
its  work  well  for  a  long  lifetime.  If  it  fails  to  do  this, 


PURE    BLOOD  AND   A  SOUND   HEART      105 

the  cause  is  usually  some  fault  for  which  we  are  our- 
selves responsible. 

Great  extremes  of  heat  and  cold  are  injurious  to  the 
heart.  Heat  stimulates  it  to  a  high  degree,  while  the 
effect  of  cold  is  to  depress  and  weaken  it  and  also 
the  small  blood  vessels.  Hence,  you  see  it  is  of  im- 
portance to  protect  the  body  by  adapting  the  clothing 
to  the  seasons  and  the  needs  of  daily  life.  It  is  espe- 
cially important  to  clothe  the  feet  well,  so  that  a  proper 
balance  of  the  circulation  may  be  maintained.  Many 
of  the  large  veins,  especially  in  the  extremities,  are 
located  near  the  surface,  and  hard  pressure  interferes 
with  the  flow  of  blood  through  them.  For  this  reason, 
elastics  on  the  arms  or  legs,  and  tight  belts  or  collars  are 
injurious. 

Very  strong  emotions  affect  the  heart  injuriously. 
Violent  anger  has  sometimes  caused  a  person  to  drop 
dead  from  sudden  heart  failure.  Even  joyful  tidings 
have  sometimes  caused  death.  Why  ?  The  lesson  to 
be  learned  from  these  facts  is  that  we  should  keep 
the  emotions  and  passions  well  under  control.  Does 
this  mean  we  should  not  be  joyful  ?  What  does  it 
mean  ? 

The  pulse  of  the  tobacco  user  indicates  unmistakably 
the  injury  which  smoking  does  to  the  heart.  It  has 
lost  its  firm,  steady  beat  and  is  feeble  and  irregular. 
This  condition  is  so  well  known  that  it  has  received 
the  name  of  "tobacco  heart."  The  tobacco  heart  has 
become  very  common  among  young  men  as  the  result 


io6  THE   BODY   IN   HEALTH 

of  cigarette  smoking.  A  large  proportion  of  those 
who  volunteer  for  military  service  are  rejected  because 
they  have  been  found  to  have  "tobacco  heart." 

Alcohol  injures  the  muscles  of  the  heart  and  the 
blood  vessels,  and  if  its  use  is  kept  up  it  may  result 
in  a  hardening  of  the  walls  of  the  arteries,  which  will 
bring  on  old  age  too  soon.  The  habitual  use  of  alcohol 
causes  the  heart  to  be  overloaded  with  fat,  which  in- 
terferes with  its  work.  In  other  cases,  its  muscular 


Pulse  beat  of  healthy  person. 


Pulse  beat  of  tobacco  user. 


Pulse  beat  of  drunkard. 

HOW   TOBACCO   AND   ALCOHOL   AFFECT  THE    HEART. 

tissue  is  changed  to  fat  and  it  loses  its  strength,  so 
that  the  heart  beat  is  a  mere  flutter.  The  muscular 
walls  of  the  small  arteries  of  the  brain  and  other  parts 
are  likely  to  undergo  a  similar  change,  and  they  may 
become  so  weak  that  they  are  not  able  to  resist  the  pres- 
sure of  the  blood.  Apoplexy  (the  bursting  of  a  blood 
vessel  in  the  brain)  is  more  frequent  among  those  who 
use  alcohol  than  among  abstainers. 

Alcohol  quickens  the  pulse,  not  by  strengthening  the 
heart,  but  by  paralyzing  the  nerve  centers  that  control 


PURE   BLOOD  AND  A  SOUND   HEART      107 

the  heart  and  the  small  blood  vessels.  In  consequence, 
the  heart  "runs  away"  as  it  were,  like  a  steam  engine 
which  has  lost  its  "governor"  or  a  clock  pendulum 
from  which  the  weight  has  been  removed.  The  red 
face  and  eyes  so  often  seen  in  a  drunkard  are  due  to  a 
paralysis  of  the  small  blood  vessels  so  that  they  are 
always  full  of  blood. 

All  these  things  show  us  that  alcohol  has  a  very  bad 
effect  upon  the  heart.  Can  one  afford  to  take  the  risk 
of  in  any  way  weakening  this  wonderful  organ  ?  In  a 
severe  illness,  everything  depends  upon  the  ability  of 
the  heart  to  stand  the  strain  of  the  disease,  and  if  it 
has  been  weakened  by  any  cause,  it  may  suddenly  fail. 
It  has  been  found  that  heavy  beer  drinkers  succumb 
very  readily  to  disease,  on  account  of  the  weakened 
condition  of  the  heart,  known  as  "beer  drinker's 
heart."  Should  you  expect  this  ?  Why  ? 

Many  of  the  headache  remedies  commonly  used  are 
manufactured  from  coal  tar,  and  these  have  a  very 
injurious  effect  upon  the  heart.  Should  medicine  of 
any  kind  ever  be  taken  except  by  the  advice  of  a 
physician?  Why? 

Severe  exercise  may  injure  the  heart  by  placing  too 
great  a  strain  on  it.  Going  to  excess  in  football, 
bicycle  riding,  and  other  severe  and  long-continued 
exercise  may  overwork  the  heart  and  cause  incurable 
disease.  The  heart,  like  any  other  muscle,  enlarges  by 
exercise.  An  enlarged  condition  of  the  heart  known 
as  "athletic  heart"  may  be  caused  by  too  severe 


io8 


THE   BODY   IN   HEALTH 


exercise.  In  this  condition  there  is  frequently  trouble 
with  the  valves  of  the  heart,  which  do  not  close  com- 
pletely, but  allow  a  leakage  of  the  blood  backward  in 
the  circulation.  This  increases  the  work  of  the  heart, 
as  some  of  the  blood  must  be  pumped  twice. 

The  heart  is  developed  and  made  strong  by  exercise, 


| 


TENNIS  is  A  GOOD  GAME,  BUT  IF  PLAYED  TOO  VIOLENTLY  THE   HEART  WILL  BE 

INJURED. 

just  as  is  any  other  muscle.  The  size  of  the  heart  is, 
HOW  to  as  a  ru^e?  proportioned  to  the  amount  of  work 
strengthen  it  has  had  to  perform.  Animals  kept  in  cages 
the  heart.  Qr  jn  capt;v;ty  have  been  found  upon  examina- 
tion after  death  to  have  much  smaller  hearts  than 
those  of  other  animals  of  the  same  species.  The  heart 
of  a  race  horse  is  much  larger  than  that  of  an  ordinary 


PURE   BLOOD  AND  A  SOUND  HEART      109 

work  horse.  The  heart  of  a  stag,  a  very  active  animal, 
is,  in  proportion  to  the  size  of  the  animal,  about  twice 
as  large  as  that  of  a  pen-fed  pig.  Can  you  tell 
why  ? 

One  who  has  a  well-developed  and  strong  heart  has 
more  vigor,  more  endurance,  and  more  courage  than 


VIGOROUS  WALKING  STRENGTHENS  THE  HEART. 

he  otherwise  would  have.  When  one  not  accustomed 
to  daily  active  exercise  hurries  to  catch  a  train  or  runs 
up  a  flight  of  stairs,  he  gets  out  of  breath  very  easily 
and  perhaps  suffers  from  a  heavy  beating  or  palpita- 
tion of  the  heart.  Enough  daily  vigorous  exercise 
should  be  taken  to  keep  the  heart  strong  and  vig- 


i io  THE   BODY  IN  HEALTH 

orous,  so  that  it  will  not  be  affected  by  moderate 
exertion. 

The  same  exercise  which  strengthens  the  legs  in 
running,  or  the  arms  in  rowing,  also  strengthens  the 
heart  by  forcing  it  to  do  the  work  necessary  to  pump 
the  blood  to  the  active  muscles,  and  carry  it  to  the 
lungs  for  purification. 

One  not  accustomed  to  exercise  should  begin  with 
a  little  at  a  time,  increasing  the  amount  as  the  heart 
becomes  stronger.  Why  ?  The  pulse  beat  and  the 
breath  will  show  how  much  exercise  it  is  safe  to  take. 
Take  a  short  run  of  about  a  minute  or  a  trot  of  a  few 
minutes  and  notice  the  effect  upon  your  breathing  and 
your  pulse.  One  should  avoid  getting  very  much  out 
of  breath  and  exciting  the  heart  to  such  a  degree  as  to 
produce  a  very  rapid  pulse.  Why  ?  The  shortness  of 
breath  occasioned  by  exercise  should  pass  away  on 
resting  a  few  minutes,  and  the  pulse  also  should  return 
to  its  ordinary  rate.  Outdoor  games  —  swimming, 
rowing,  walking,  and  especially  mountain  climbing  — 
are  excellent  forms  of  exercise  for  strengthening  the 

heart. 

HEALTH  PROBLEMS 

1.  Can  you  tell  when  you  look  at  a  person  whether  or  not  his 
blood  is  pure  ?     Mention  all  the  signs  that  indicate  impurity. 

2.  Can  you  tell  when  a  person  has  not  had  sleep  enough  ? 
Describe  all  the  signs  of  lack  of  sleep. 

3.  Have  you  ever  noticed  the  eyes  and  skin  of  a  drunkard  ? 
If  so,  do  they  seem  like  the  eyes  and  skin  of  other  people  ?     Why 
does  the  end  of  a  drunkard's  nose  seem  so  red  ? 


PURE   BLOOD  AND  A  SOUND   HEART      in 

4.  Can  a  person  who  works  at  a  desk  all  day  and  who  does 
not  take  exercise  in  the  open  air  keep  his  blood  from  becoming 
impure  ?     Explain. 

5.  Should  you  expect  to  find  pure  blood  in  people  who  were 
living  all  the  time  in  a  town  or  city  where  the  sun  could  not  shine 
because  of  the  smoke  and  dust  ?     Explain. 

6.  A  good  many  people  think  they  have  to  take  blood  purifiers 
in  the  spring.     Why  should  they  feel  the  need  of  such  things 
especially  in  the  spring  ?     Do  you  think  they  can  get  their  blood 
purified  by  taking  such  medicines  ? 

7.  Do  you  take  cold  baths  ?     If  so,  describe  all  your  experi- 
ences from  the  moment  the  first  drop  touches  you  until  you  are 
through  with  the  bath. 

8.  Do  you  think  it  would  be  wise  for  a  weak  person  who  is  not 
accustomed  to  cold  baths  to  jump  into  a  tub  of  very  cold  water 
or  into  a  cold  river  or  a  cold  lake  ? 

9.  I  have  known  boys  who  wore  very  tight  belts  to  hold  up 
their  trousers.     Do  you  think  they  are  likely  to  be  injured  in  this 
way  ?     Why  ? 

10.  Why  will  no  boy  or  man  who  uses  tobacco  or  alcohol  be 
allowed  to  go  on  an  athletic  team  in  the  high  schools  or  colleges  ? 

11.  Have  you  known  people  who  would  get  out  of  breath  if 
they  even  walked. rapidly  ?     What  is  probably  the  matter  with  such 
people  ?     How  long  can  you  run  without  getting  out  of  breath  ? 

12.  Does  one  need  to  take  special  heart  exercises  or  will  the 
heart  take  care  of  itself  if  one  lives  right,  —  that  is,  if  he  takes 
enough  food  for  his  needs,  exercises  regularly  so  as  to  keep  his 
body  and  muscles  in  good  condition,  keeps  from  putting  poisons 
into  his  body,  and  so  on  ? 

REVIEW  QUESTIONS 

1.  Upon  what  does  the  life  of  the  body  depend  ? 

2.  Why  should  blood  cells  be  kept  in  good  fighting  condition  ? 


ii2  THE   BODY  IN  HEALTH 

3.  Suppose  the  blood  is  impure;  what  happens  to  every  cell  in 
the  body  ? 

4.  How  do  alcoholic  drinks,  such  as  whisky  and  beer,  affect 
the  blood  ?     How  can  you  tell  a  person  who  habitually  drinks 
wine  and  whisky  in  large  quantities  ? 

5.  What  is  the  effect  of  such  things  as  pepper  and  mustard  on 
the  body  ? 

6.  How  does  eating  affect  the  blood  ?     How  does  sleep  ? 

7.  What  will  happen  to  the  blood  if  the  wastes  are  not  got  rid 
of? 

8.  What  organs  have  to  do  mainly  with  getting  rid  of  wastes  ? 

9.  Why  is  water  valuable  in  keeping  the  blood  pure  ? 

10.  Can  one  make  the  blood  pure  by  taking  pills  ?  Why  ? 
What  is  the  only  way  in  which  one  can  make  his  blood  pure  ? 

n.  Mention  all  the  benefits  that  come  from  cold  baths  if  one 
can  take  them. 

12.  Why  is  it  necessary  to  have  a  strong  heart  ? 

13.  If  one  does  not  illtreat  his  heart,  how  long  will   it  serve 
him  ? 

14.  Tell  how  these  things  affect  the  heart:    clothing;    strong 
emotions,  as  anger  or  the  like;    tobacco;    alcohol;    very  severe 
exercise. 

15.  Why  do  people  who  use  a  good  deal  of  tobacco  and  alcohol 
seem  less  able  to  resist  diseases  than  others  ? 

16.  Should  one  use  hea,dache  remedies  without   consulting   a 
physician  ? 

17.  How  can  one  strengthen  his  heart  so  that  it  will  be  ready  for 
any  need  of  daily  life  ? 


CHAPTER   VII 
THE  BREATH  OF  LIFE 

FROM  what  you  have  already  learned  you  know  that 
we  breathe  to  obtain  the  life-giving  gas  called  oxygen 
and  to  expel  the  poisonous  gas  called  carbon  oxygen, 
dioxide  which  is  formed  in  all  living  things,  theiife- 
Every  one  of  the  many  millions  of  minute  s^gg*8- 
living  creatures  or  cells  of  which  the  body  is  made  up 
must  breathe  in  order  to  live.  That  is,  it  must  get  a 
constant  supply  of  oxygen  and  must  get  rid  of  its  car- 
bon dioxide.  Oxygen  is  absolutely  essential  to  life. 
Its  great  use  in  the  body  is  to  set  free  or  bring  into 
action  the  energy  stored  in  the  body  in  the  form  of 
digested  and  assimilated  food.  We  have  found  that 
the  body  gets  its  warmth  and  power  to  work  from 
the  burning  or  oxidation  of  these  food  substances  in 
the  cell.  We  know  that  the  burning  of  wood  or  coal 
in  a  stove  can  not  take  place  without  oxygen.  If  a 
stove  is  made  air  tight  by  shutting  up  all  the  draughts, 
the  fire  will  burn  low  and  after  a  while  go  out  alto- 
gether. Oxygen  is  just  as  necessary  for  the  burning 
of  food,  the  fuel  of  the  body, 
i  113 


ii4  THE   BODY   IN   HEALTH 

The  cells,  packed  as  they  are  in  the  interior  of  the 
body,  cannot  get  their  oxygen  directly  from  the  air, 
as  the  amoeba  can  from  the  water.  It  must  therefore 
be  taken  into  the  body  and  carried  to  them.  In  the 
division  of  labor  among  the  cells,  the  work  of  taking 
into  the  body  the  supply  of  oxygen  needed  by  the  cells  and 
expelling  the  carbon  dioxide  formed  by  them  is  given 
to  the  lungs.  Just  as  the  digestive  organs  prepare 
the  food  for  all  the  cells,  so  the  lungs  supply  the  oxygen 
for  all  the  cells.  The  digestive  organs  get  their  oxygen 
from  the  lungs,  the  lungs  get  their  food  supply  from 
the  digestive  organs,  and  so  also  every  body  cell  by  its 
work  helps  every  other  cell. 

There  must,  of  course,  be  some  means  of  communi- 
cation between  the  lungs  and  the  cells,  by  which  the 
oxygen  from  the  lungs  may  reach  the  cells,  and  the 
carbon  dioxide  from  the  cells  may  reach  the  lungs. 
This  is  provided  for  by  the  circulation  of  the  blood, 
which  is,  as  we  have  seen,  a  carrier  between  the  lungs 
and  the  tissues  as  well  as  between  the  digestive  organs 
and  the  tissues. 

The  air  is  sucked  into  the  lungs  by  means  of  a  tube 
called  the  windpipe  or  trachea,  which  at  its  upper  end 
The  is  widened  into  a  small  chamber  called  the 

breathing  larynx,  a  box  made  of  cartilage  in  which  the 
apparatus.  vocaj  cor(js  are  placed,  and  which  communi- 
cates with  the  air  through  the  nose  and  mouth.  At 
its  lower  end,  the  trachea  is  divided  into  two  branches, 
called  bronchial  tubes,  one  of  which  passes  to  the  right 


THE   BREATH  OF  LIFE 


and  one  to  the  left  of  the  chest.  Each  of  these  is 
divided  and  subdivided  like  the  branches  of  a  tree 
into  innumerable  smaller  tubes  or  bronchi,  the  very 
smallest  of  which  are  called  bronchioles.  The  bronchi- 


THE  HEART  AND  BREATHING  APPARATUS. 

I,  heart;  2,  lung;  3,  pericardium;  4,  pleura;  5,  diaphragm;  6,  larynx;  7,  trachea; 
8,  bronchioles;  9,  bronchial  tube. 

oles  end  in  small  pouches,  the  sides  of  which  are  every- 
where pitted  with  little  recesses  or  tiny  sacs  called  air 
cells.  The  total  number  of  air  cells  in  the  lungs  has 
been  estimated  to  be  not  less  than  1,70x3,000.  The 
term  cell  is  here  used  in  its  ordinary  sense,  meaning  a 


n6  THE   BODY  IN   HEALTH 

small  chamber,  and  not  in  the  sense  in  which  we  used 
it  in  previous  chapters.  What  did  it  mean  then  ? 

The  air  cells  and  air  tubes  are  bound  together  by 
means  of  tissues  in  which  there  are  a  large  number  of 
elastic  fibers.  These  enable  the  lungs  to  stretch  or 
expand  when  they  are  filled  with  air.  The  whole  is 
completely  enclosed  in  a  membrane  called  the  pleura. 

The  great  purpose  of  the  lungs  is,  of  course,  to  bring 
the  blood  in  contact  with  the  air.  The  lining  mem- 
brane of  the  air  cells  is  of  such  marvelous  thinness  that 
2500  layers  would  make  but  an  inch  in  thickness.  On 
account  of  the  immense  number  of  air  cells  and  minute 
air  tubes,  the  extent  of  this  membrane  is  so  great  that 
if  it  were  spread  out  over  a  flat  surface  it  would  cover 
hundreds  of  square  feet.  Immediately  under  this  deli- 
cate membrane,  in  the  walls  of  the  air  cells,  is  a  very 
remarkable  network  of  capillaries,  which  as  you  already 
know  are  minute  blood  vessels.  The  blood  which  passes 
through  this  wonderful  capillary  network  is,  by  reason 
of  the  thinness  of  the  lining  membrane,  exposed  to  the 
air  in  the  most  thorough  manner  possible.  All  the 
blood  in  the  body  passes  through  the  lung  capillaries 
once  every  minute  and  a  quarter. 

The  passages  which  lead  to  the  lungs  begin  with  the 
mouth  and  the  nostrils.  The  nostrils  lead  to  the  nasal 
cavity.  This  cavity  is  divided  for  about  one  half  its 
length  by  means  of  a  partition  called  the  septum.  The 
sides  of  the  nasal  cavity  are  covered  with  mucous  mem- 
brane, the  extent  of  which  is  greatly  increased  by  scroll- 


THE   BREATH  OF  LIFE 


117 


like  projections  of  bone  and  cartilage  from  the  outer 
walls  of  the  cavity,  as  you  see  in  the  picture.  The  nasal 
cavity  and  the  cavity  of  the  mouth  unite  at  their  back 
parts  to  form  the  pharynx,  which  is  separated  from 
the  mouth  by  a  hanging 
partition,  —  the  soft  palate. 
Everything  which  enters  the 
lungs  and  the  stomach 
passes  through  the  pharynx. 
On  either  side  of  the  phar- 
ynx are  the  tonsils,  two  re- 
markable glands  which  are 
placed  at  the  entrance  to 
the  body  to  protect  it 
against  germs  which  enter 
with  the  air  and  food. 

When  germs  are  present  in 
such  great  numbers  that  the 
tonsils  are  not  able  to  de- 
stroy them  all,  some  of  the 
germs  penetrate  the  tissues  and  the  tonsils  become  in- 
fected. The  germs  creep  down  into  little  crypts  or  pock- 
ets, of  which  the  tonsils  are  full.  They  fill  these  pockets 
with  germs  as  a  boy  may  fill  his  pocket  with  marbles. 
Sometimes  so  many  germs  cluster  upon  the  tonsils  that 
they  become  overwhelmed  and  lose  their  power  to  de- 
stroy the  germs  ;  the  result  is  that  the  germs  destroy  the 
tonsil.  The  tonsils  then  become  inflamed  and  enlarged, 
and  quite  frequently  their  removal  is  necessary.  In- 


WHY    DID     NATURE    PLACE   THE    TON- 
SILS   WHERE    YOU    SEE    THEM  ? 

I,  rivula;  2,  pillars  of  fauces; 
3,  tonsils. 


THE   BODY   IN   HEALTH 


fection  from  diseased  tonsils  may  be  carried  to  the 
lymph  glands  of  the  neck  and  to  the  lungs,  and  en- 
larged glands  or  tuberculosis  may  result.  One  of  the 

best  means  of  pro- 
tecting the  tonsils  is 
by  breathing  plenty 
of  pure,  cold,  fresh 
air.  Dust-laden  air 
should  be  avoided. 

Just  beyond  the 
root  of  the  tongue, 
in  the  front  wall  of 
the  pharnyx,  is  an 
opening  called  the 
glottis,  which  leads 
into  the  larynx,  the 
entrance  to  the  wind- 
pipe. The  glottis  is 
guarded  by  a  closely 
fitting  covering 
called  the  epiglottis, 
consisting  of  a  leaf- 
shaped  cartilage,  one 
side  of  which  is  hinged  at  the  root  of  the  tongue  in 
such  a  manner  that,  in  the  act  of  swallowing,  the  cover 
is  tightly  closed,  preventing  the  entrance  of  food  or 
drink  into  the  windpipe.  The  pharynx  itself  leads  to 
the  esophagus,  or  food  pipe. 
The  whole  of  the  breathing  apparatus  is  lined  with 


THE  ROUTE  WHICH  THE  AIR  AND  THE  FOOD  TAKE 
ON  THE  WAY  TO  THE  LUNGS  AND  THE  STOMACH. 

I,  tongue;  2,  pharynx;  3,  epiglottis; 
4,  larynx;  5,  trachea;  6,  esophagus. 


THE   BREATH  OF  LIFE  119 

mucous  membrane,  which  is  kept  moist  with  mucus. 
Particles  of  dust  and  germs  which  are  carried  down 
into  the  air  passages  are  caught  by  this  mucus,  much 
as  flies  are  caught  on  a  sticky  fly  paper.  Except  in 
the  air  cells  and  the  pharynx,  the  walls  of  the  air  pas- 
sages may  be  shown  by  the  microscope  to  be  covered 
by  minute  hairs.  By  the  constant  movement  of  these 
hairs,  or  cilia  as  they  are  called,  a  stream  of  mucus 
is  swept  upwards  towards  the  mouth,  carrying  with 
it  the  captured  dust  and  germs.  In  this  way  the 
air  is  cleansed,  and  dust  and  germs  are  in  a  great 
measure  prevented  from  reaching  the  air  cells  of  the 
lungs. 

If  you  could  watch  the  blood  as  it  passes  through 
the  lung  capillaries,  you  would  see  a  remarkable  change 
taking  place  in  it.     The  dark  purplish  hue  ^^ 
•which  it  has  when  it  enters  the  capillaries  is  takes  place 
changed  for  a  bright  crimson  before  it  leaves  **ihe 
them  and  starts  for  the  heart.     What  is  the 
reason  for  this  wonderful  change  of  color  ?     It  means 
that  there  has  been  an  actual  change  in  the  quality  of 
the  blood.     A  part  of  its  cargo  of  carbon  dioxide  has 
been  discharged,  and  a  fresh  load  of  oxygen  taken  on 
board  by  the  red  cells.     That  is,  as  the  blood  flows 
through  the  capillaries  in  the  lungs,  it  gives  off  carbon 
dioxide  into  the  air  sacs  and  receives  in  its   place  a 
fresh  supply  of  oxygen. 

The  opposite  kind  of  change  you  would  see  taking 
place  in  the  capillaries  of  the  body.     Here  the  blood 


120 


THE   BODY  IN  HEALTH 


loses  its  bright  crimson  color  and  takes  on  a  darker 
hue.     The  oxygen   received   from  the  lungs  is,  when 


WHEN  THE  BREATH  GOES  OUT. 


WHEN  THE  BREATH  GOES  IN. 


the  blood  reaches  the  capillaries  anywhere,  sent  through 
the  thin  walls  of  the  vessels  into  the  lymph.  The  cells 
take  up  the  oxygen  from  the  lymph  in  which  they  live 


THE   BREATH  OF  LIFE  121 

(just  as  the  one-celled  animal  takes  its  oxygen  from 
the  water)  and  discharge  into  it  their  carbon  dioxide, 
which  is  sent  from  the  lymph  into  the  capillaries. 
Just  as  in  the  lung  capillaries  the  blood  gives  up 
carbon  dioxide  and  takes  on  oxygen,  so  in  the  capil- 
laries of  the  other  tissues  it  gives  up  oxygen  and  takes 
on  carbon  dioxide  ;  and  it  is  this  change  which  causes 
it  to  darken  in  color.  For  this  reason  the  blood  in  the 
arteries,  which  carry  the  purified  blood  from  the  heart, 
is  much  brighter  in  color  than  that  in  the  veins,  which 
return  the  impure  blood  to  the  heart.  It  is  this  dark 
color  of  the  blood  that  causes  the  veins  that  can  be 
seen  through  the  skin  to  appear  blue. 

The  change  that  takes  place  in  the  blood  in  the  lung 
capillaries  causes  a  corresponding  change  in  the  air  in 
the  lungs.  The  double  process  of  taking  oxygen  out 
of  it  and  putting  carbon  dioxide  into  it  spoils  the  air 
and  makes  it  necessary  that  it  should  be  constantly 
renewed.  A  constant  change  of  air  in  the  lungs  is 
essential  to  life.  Why  ? 

Breathing  has  for  its  purpose  to  ventilate  the  lungs 
by  putting  fresh  air  into  them.     Do  we  at  each  breath 
expel  all  the  air  in  the  lungs  and  take  in  an  How  the 
entire  new  supply  ?     As  a  rule  only  from  one  lungs  are 
tenth  to  one  fifth  part  of  the  air  in  the  lungs  is  ventUated- 
changed  every  time  we  breathe. 

The  air  is  brought  into  the  lungs  by  a  most  wonder- 
ful pumping  device.  The  lungs  are  suspended  in  an 
air-tight  box,  —  the  chest  cavity  or  thorax.  The  ribs 


122  THE   BODY  IN  HEALTH 

with  the  muscles  and  other  tissues  that  cover  them 
form  the  sides  of  the  thorax.  The  backbone  and  the 
chest  bone  also  help  to  form  the  chest  walls.  The 
floor  or  under  side  of  the  cavity  is  formed  by  a  broad 
strong  muscle  called  the  diaphragm,  which  separates 
the  thorax  from  the  abdomen. 

The  diaphragm  acts  very  much  like  the  piston  of  a 
pump.  It  moves  up  and  down,  pulling  the  air  into 
the  lungs  as  it  descends. 

Air  is  made  to  enter  the  lungs  by  enlarging  the  chest 
cavity  or  thorax.  This  is  accompanied  by  a  down- 
ward movement  of  the  diaphragm  and  an  outward 
movement  in  all  directions  of  the  side  walls  of  the 
chest.  This  widening  is  done  by  means  of  the  muscles 
which  lift  the  ribs  and  pull  them  outward.  When 
these  muscles  cease  their  pulling,  the  chest  walls  return 
to  their  former  position,  and  the  air  which  was  sucked 
into  the  lungs  by  enlarging  the  chest  is  forced  out 
again.  The  natural  elasticity  of  the  lungs  and  the 
contraction  of  the  muscles  of  the  abdomen  also  aid  in 
expelling  the  air.  The  lungs  act  much  like  a  pair  of 
bellows,  except  that  the  air  passes  out  and  in  at  the 
same  opening.  The  windpipe  is  the  nozzle  of  the 
bellows,  the  lungs  the  body,  and  the  points  of  the  ribs 
on  either  side  the  two  handles.  When  the  muscles 
contract,  the  points  of  the  ribs  are  separated,  just  as 
the  handles  of  a  pair  of  bellows  are  drawn  apart.  This 
may  easily  be  seen  in  the  panting  of  a  dog,  or  in  the 
breathing  of  a  long-distance  runner. 


THE  BREATH  OF  LIFE 


123 


There  are  thus  two  acts  in  breathing :  the  first,  or 
drawing  in  of  the  breath,  is  called  inspiration  ;  the 
second,  or  sending  out  of  the  breath,  is  called  expira- 
tion. As  a  rule  the  lungs  act  once  for  every  four  heart 
beats.  See  how  long  you  can  hold  your  breath.  It 
is  not  ordinarily  possible  to  do  this  for  more  than  half 
a  minute,  but  if  you  take  several  deep  inspirations,  you 
will  find  you  can  hold  the  breath  much  longer.  Why  ? 
The  very  longest  time,  however,  that  the  breath  can 
be  held  even  by  those  most  practiced  in  it,  such  as 
deep  sea  divers,  is  three  minutes. 


NATURAL  FORM. 


EFFECT  OF  TIGHT  LACING. 


In  natural  breathing,  when  the  movements  are  not 
in  any  way  interfered  with,  there  is  a  movement  of 
the  whole  trunk,  chiefly  in  the  region  of  the  Howto 
waist.     There  are  two  very  harmful  modes  of  breathe 
breathing   which  must    be   avoided.     One  of  correctly- 
these  is  called  costal  or  "rib"  breathing,  in  which  the 


124  THE   BODY   IN   HEALTH 

movement  is  chiefly  in  the  upper  part  of  the  chest  and 
the  diaphragm  does  scarcely  any  work.  This  style  of 
breathing  is  common  among  civilized  women,  for  the 
reason  that  they  constrict  the  body  with  corsets  and 
other  tight  garments  and  so  interfere  with  the  move- 
ments of  the  diaphragm  and  the  lower  rib  muscles. 
The  work  of  the  diaphragm  assists  the  circulation  and 
the  digestion  as  well  as  the  breathing,  and  anything 
that  interferes  with  its  action  must  be  injurious. 

This  style  of  breathing  is  so  common  among  civilized 
women  that  it  has  given  rise  to  the  idea  that  they 
naturally  breathe  in  a  different  way  from  men,  with  the 
upper  part  of  the  chest  alone.  This  idea  is  shown  to 
be  incorrect  by  the  fact  that  boys  and  girls  and  un- 
civilized men  and  women  breathe  in  exactly  the  same 
manner.  An  examination  of  the  most  primitive  Indian 
tribes  in  the  United  States,  also  careful  observations 
of  Chinese,  Mexican,  Egyptian  and  Arab  women, 
whose  clothing  has  never  been  such  as  to  interfere  with 
the  natural  breathing  movements,  showed  that  women 
naturally  breathe  in  precisely  the  same  way  as  men, 
by  an  expansion  of  the  whole  chest,  particularly  the 
lower  part. 

Another  unnatural  style  of  breathing  is  called 
"abdominal  breathing,"  which  is  most  common  among 
men  who  lead  sedentary  lives,  in  whom  the  muscles 
of  the  abdomen  are  usually  weakened.  The  weakened 
muscles  yield  to  the  downward  pressure  of  the  dia- 
phragm, and  the  abdomen  bulges  forward ;  but  there 


THE   BREATH   OF  LIFE  125 

is  very  little  movement  of  the  rib  muscles.  The 
diaphragm  does  all  the  work,  and  the  upper  thorax 
does  not  expand  at  all.  This  greatly  interferes  with 
the  proper  ventilation  of  the  lungs. 

Neither  costal  nor  abdominal  breathing  brings  the 
lungs  fully  into  action.  In  those  parts  that  remain 
idle,  the  air  stagnates,  and  carbon  dioxide  and  other 
poisons  accumulate.  The  germs  of  pneumonia  and 
tuberculosis  and  other  disease-producing  microbes  are 
likely  to  find  lodgment  in  these  idle  parts.  Should  the 
breathing  movements  be  such  as  to  expand  and  bring 
into  action  all  portions  of  the  lungs  ? 

The  muscles  of  the  abdomen  are  of  assistance  to  us 
in  breathing.  As  the  breath  is  drawn  in  when  the  chest 
is  fully  expanded,  the  abdominal  muscles  are  stretched 
and  made  tense,  because  of  the  pressure  of  the  dia- 
phragm upon  the  organs  contained  in  the  abdomen. 
In  expiration,  these  muscles  contract,  as  does  rubber 
released  after  stretching ;  and  by  pushing  the  abdomi- 
nal organs  upward  again,  they  aid  in  crowding  the  air 
out  of  the  lungs,  and  in  preparing  for  another  incoming 
breath.  In  order  to  serve  this  useful  purpose,  the 
abdominal  muscles  must,  of  course,  be  kept  vigorous 
by  exercise. 

The  proper  passage  for  the  air  to  pass  into  the  lungs 
is  through  the  nostrils,  which  are  especially  fitted  for 
purifying  and  warming  it.  The  nostrils  are  guarded 
by  hairs  for  straining  out  dust,  and  the  mucus  also 
catches  dust  and  germs.  The  nose  not  only  acts  as  a 


126 


THE  BODY  IN  HEALTH 


strainer,  but  it  also  warms  the  air,  moistens  it  when 
too  dry,  and  warns  us  when  it  is  impure. 

Many  persons  acquire  the  harmful  habit  of  breath- 
ing through  the  mouth.  Mouth  breathing  in  children 
is  usually  caused  by  adenoids,  a  growth  of  tissue  which 
often  nearly  fills  the  breathing  passages.  You  know 


BEFORE  AND  AFTER  REMOVAL  OF  ADENOIDS. 

how  uncomfortable,  how  stuffy  and  stupid  you  feel 
when  the  nasal  passages  are  obstructed  by  means  of  a 
"cold  in  the  head."  The  boy  or  girl  who  has  adenoids 
is  always  in  this  condition.  As  a  result  of  the  obstruc- 
tion of  the  air  passages,  the  whole  body  suffers  for  lack 
of  oxygen.  The  mouth  breather  can  usually  be  dis- 
tinguished by  his  peculiar  expression  and  half-dazed 
condition.  He  is  inattentive  and  cannot  understand 


THE   BREATH  OF  LIFE 


127 


or  study  well.  His  eyes  are  usually  dull,  his  expression 
stupid,  and  the  open  mouth,  which  is  necessary  for  the 
passage  of  air,  adds  to  the  unattractiveness  of  his 
appearance.  Sometimes  as  a  result  of  mouth  breath- 
ing the  features  be- 
come distorted,  the 
upper  lip  becomes 
shortened,  and  the 
upper  teeth  project. 
Adenoids  are  fre- 
quently a  cause  of 
deafness.  A  phy- 
sician should  always 
be  consulted  when 
mouth  breathing  is 
found  to  be  a  habit. 
Removal  of  the 
adenoids  is  a  very 
simple  matter,  but 

their     effects      if     al-   •  WHERE  ADENOIDS  ARE  FOUND. 

lowed  to  remain  are  serious  and  may  affect  the  whole 
after  life.  . 

"To  breathe  well  is  to  live  well, — to  live  longer  and 
better." 

While  the  lungs  are  to  some  extent  under  our  con- 
trol, still  their  action  is,  like  that  of  the  heart,  auto- 
matic, or  self-regulating.  During  sleep  as  well  as  dur- 
ing waking  hours,  their  movements  are  carried  on  with 
rhythmical  regularity  The  breathing  is  not  so  deep 


128  THE   BODY  IN  HEALTH 

during  sleep  as  during  activity.  It  is  also  slower.  Less 
oxygen  is  used  when  the  body  is  asleep,  and  this  results 
in  lessened  breathing.  The  work  of  the  liver  and  the 
kidneys  and  the  repairing  work  of  the  cells  goes 
on  during  sleep,  and  this  requires  oxygen.  Hence 
the  body  should  be  supplied  with  an  abundance  of 
fresh  air  during  sleep  by  proper  ventilation  of  the  sleep- 
ing rooms.  The  amount  of  air  taken  in  during  sleep 
may  be  increased  by  enlarging  the  capacity  of  the 
lungs  by  suitable  exercise  while  one  is  awake.  It  has 
been  found  by  experiment  that  the  amount  of  air  taken 
into  the  lungs  during  sleep  was  doubled  in  students 
whose  breathing  capacity  had  been  increased  by  exercise. 
The  act  of  breathing  is  a  blood-pumping  process,  as 
well  as  the  means  by  which  air  is  moved  in  and  out  of 
the  lungs.  The  enlarging  of  the  thorax,  by 
?owt, .  means  of  which  air  is  sucked  into  the  lungs, 

breathing  .  111 

aids  the  also  works  at  the  same  time  to  suck  the  blood 
circulation  Up  toward  the  great  veins  that  lead  to  the 
digestion  heart.  At  the  same  moment,  the  downward 
pressure  of  the  diaphragm,  which  presses  the 
abdominal  organs  against  the  muscular  walls  of  the 
abdomen,  serves  to  force  the  blood  upward.  This 
empties  the  blood  of  the  veins  in  the  abdominal  cavity 
into  the  chest,  thus  helping  it  on  toward  the  heart. 
You  can  see  then  that  deep  breathing  aids  the  cir- 
culation of  the  blood. 

The  stomach  lies  just  below  the  diaphragm,  which, 
as  it  moves  up  and  down,  kneads  the  stomach  and  its 


THE   BREATH  OF  LIFE  129 

contents  and  so  assists  the  work  of  mingling  the  foods 
and  the  digestive  fluids.  In  ordinary  breathing  in  a 
quiet  person,  the  movements  of  the  chest  are  slight,  and 
the  action  of  the  diaphragm  produces  little  effect ;  but 
by  moderate  exercise  the  movements  are  more  than 
doubled,  and  the  stomach  is  then  kneaded  in  a  vigorous 
manner.  In  this  way  moderate  exercise  after  eating  is 
beneficial,  though  violent  exercise  should  be  avoided. 
Why  ?  Would  the  practice  of  taking  breathing  exer- 
cises after  meals  be  helpful  to  digestion  ?  Why  ? 

The  use  of  alcohol  or  tobacco  is  injurious  to  the 
respiratory  passages  and  the  lungs,  as  you  might  ex- 
pect. You  already  know  that  alcohol  greatly 

11  c    i      i       i  -  Effects  of 

weakens  the  power  of  the  body  to  resist  germs,  ^hoi 
One  who  uses  alcohol  is  therefore  especially  and 
liable  to  attacks  of  grip  and  pneumonia,  as  well  tj)bacco  on 

i       r    i  T-I  the  lungs. 

as  to  catarrh  or  the  air  passages.  I  he  smoke 
of  cigarettes  contains  a  poisonous  gas  called  carbon 
monoxide.  When  this  smoke  is  inhaled,  as  it  frequently 
is  by  smokers,  both  the  poisonous  gas  and  the  tobacco 
poison  get  into  the  blood  in  the  lung  capillaries  and 
are  a  source  of  injury  to  the  cells. 

Nothing  is  of  more  importance  for  a  long  and  vigor- 
ous life  than  large  lung  capacity.     By  means  of  an 
instrument  called  the  spirometer,  into  which  Deveioping 
a  person  breathes  after  taking  a  deep  inspira-  lung 
tion,  it  is  possible  to  find  out  the  vital  capacity,  caPacity- 
that  is,  the  amount  of  air  change  which  takes  place 
in  the  lungs,     A  person's  lung  strength  can  be  learned, 


130 


THE   BODY  IN  HEALTH 


however,  without  the  use  of  the  spirometer,  by  testing 
the  ability  to  endure  exercise  which  taxes  breathing 
power,  such  as  running  up  and  down  stairs  or  other 
running  exercises.  Extreme  breathlessness  caused  by 
moderate  exercise  indicates  either  that  the  heart  is 

weak  or  that  the  breathing  capac- 
ity needs  developing. 

Any  exercise  which  compels  full, 
deep  breathing  is  a  valuable  means 
of  developing  the  lung  capacity. 
Breathing  power  depends  upon  the 
strength  of  the  muscles  that  con- 
trol the  chest  walls,  as  well  as 
upon  the  size  of  the  chest.  Exer- 
cise in  a  gymnasium,  chopping 
and  sawing  wood,  digging,  laundry 
work,  scrubbing,  and  all  sorts  of 
active  housework  and  farm  work 
are  excellent  means  of  develop- 
ing the  chest.  Should  you  expect 
this  ?  Why  ? 
When  a  chest  is  not  stretched  to  its  fullest  capacity 
many  times  daily,  it  is  likely  to  lose  its  capacity, 
especially  after  the  age  of  thirty.  The  proper  time 
for  chest  development  is  in  childhood  and  youth.  Dur- 
ing this  period  the  soundness,  of  the  heart  makes  it 
possible  to  take  without  injury  those  vigorous  exer- 
cises which  are  necessary  to  secure  the  highest  degree 
of  lung  capacity. 


ENLARGING  THE  CHEST. 


THE   BREATH  OF  LIFE  131 

We  have  seen  that  the  breathing  movements  are  for 
the  purpose  of  supplying  the  cells  with  oxygen,  and 
the  breathing  is  therefore  regulated  according  to  the 
needs  of  the  cells.  When  the  large  muscles  of  the 
body  are  actively  at  work,  as  in  running,  oxygen  is 
rapidly  used  up  by  the  working  cells,  and  the  blood  is 
filled  with  carbon  dioxide.  The  heart  beats  more 
rapidly  to  send  the  impure  blood  to,  the  lungs  for 
purification  and  a  supply  of  oxygen.  In  this  way  a 
sort  of  thirst  for  air  is  created  and  deep  and  rapid 
breathing  is  the  result.  Exercises  of  this  sort  are  far 
superior  to  so-called  "breathing  exercises,"  in  which 
the  lungs  are  forcibly  compelled  to  take  in  more  than 
the  ordinary  amount  of  air,  though  these  latter  exer- 
cises have  some  value.  The  impulse  which  comes  from 
within,  from  the  so-called  "respiratory  centers, "stimu- 
lates the  respiratory  muscles  so  that  they  cause  the  chest 
to  execute  the  strongest  breathing  movements  with  the 
greatest  ease,  ventilating  every  portion  of  the  lungs  and 
filling  every  air  cell  to  the  utmost  capacity. 

Running,  or  other  active  exercise  of  the  leg  muscles, 
is  an  excellent  means  of  increasing  the  lung  capacity. 
At  first  the  breathing  is  slightly  difficult,  but  after  a 
short  time,  when  the  runner  has  his  "second  wind," 
respiration  becomes  easier.  The  entire  lung  surface 
is  then  brought  into  action.  There  is  an  important 
lesson  in  this,  —  namely,  that  in  ordinary  breathing 
the  entire  lungs  are  not  brought  into  use  and  hence 
are  likely  to  become  diseased,  unless  brought  into  full 


132  THE   BODY  IN   HEALTH 

use  by  exercises  which  necessitate  deep  and  full  respira- 
tion. Runners  always  have  large  and  active  chests, 
and  sedentary  persons  have  chests  of  limited  capacity 
and  rigid  walls. 

Probably  the  best  of  all  exercises  for  developing  the 
breathing  powers  is  swimming.  The  position  of  the 
body  and  the  active  movements  of  the  arms  and  legs 
make  swimming  a  most  effective  breathing  exercise. 
The  contact  of  the  skin  with  the  cold  water  also  stimu- 
lates the  movements  of  the  chest,  while,  by  increasing 
the  energy  of  the  muscles  it  produces  vigorous  mus- 
cular movements.  Even  the  ordinary  daily  bath  is  an 
excellent  means  of  enlarging  respiration.  It  deepens 
the  breathing,  and  this  in  time  results  in  greater  lung 
capacity.  It  also  increases  the  circulation  of  the  blood 
in  the  lungs,  which  means  greater  absorption  of  oxygen. 
The  daily  cold  bath,  by  increasing  the  resistance  of 
the  body,  prevents  colds,  which  are  injurious  to  the 
respiratory  passage  and  other  more  serious  diseases  of 
the  lungs.  In  experiments  made  with  young  people 
the  girth  or  size  of  the  chest  was  increased  in  some 
cases  one  and  one  half  inches  in  three  weeks  as  a  result 
of  cold  bathing. 

We  need  a  large  amount  of  air.  We  require  a  pint 
of  air  at  every  breath.  If  you  can  take  more,  it  is  all 
the  better.  A  consumptive  often  does  not  take  half 
that.  A  pint  every  breath,  sixteen  breaths  a  minute, 
equals  two  gallons  every  minute  ;  that  amounts  to  120 
gallons  an  hour,  almost  3000  gallons  a  day.  Three 


THE   BREATH  OF  LIFE  133 

thousand  gallons  would  be  how  many  barrels  ?  — 
nearly  100  barrels  of  air.  That  is  the  daily  ration  of 
air. 

Special  breathing  exercises,  as  well  as  those  mus- 
cular movements  which  create  a  "thirst  for  air,"  are 
beneficial  to  the  lungs  by  keeping  the  chest  flexible 
and  ventilating  the  lungs.  These  movements  also 
exercise  a  beneficial  effect  upon  the  digestive  organs 
lying  below  the  diaphragm,  as  we  saw  in  a  previous 
chapter.  Every  time  the  diaphragm  contracts  it  gives 
these  organs  a  hearty  squeeze,  so  to  speak,  emptying 
out  the  blood  contained  in  them,  as  one  may  empty  a 
moist  sponge  by  pressure  upon  it.  All  exercises  which 
increase  the  strength  of  the  abdominal  muscles  are  a 
means  of  aiding  and  improving  the  breathing. 

One  should  make  a  practice  of  taking  some  kind  of 
breathing  exercises  for  a  few  minutes  several  times  a 
day.  They  should  of  course  be  taken  outdoors  where 
the  air  is  pure.  A  convenient  time  is  on  the  way  to 
and  from  school.  Simply  filling  the  lungs  with  air 
until  every  part  is  expanded  and  then  slowly  exhaling 
it  is  very  beneficial.  Do  this  several  times  in  succes- 
sion. When  you  are  tired  or  feel  dull  and  stupid,  try 
the  effect  of  going  outdoors  or  opening  a  window  and 
taking  a  few  deep  breaths.  You  will  be  surprised  to 
see  how  this  will  rest  and  refresh  you  and  sweep  the 
cobwebs  from  your  brain.  After  being  shut  up  in  a 
close  room  or  in  an  ill-ventilated  hall  or  church,  be  sure 
to  ventilate  the  lungs  thoroughly  on  coming  out  by 


134 


THE   BODY  IN  HEALTH 


taking  a  few  deep-breathing  movements.  Tiredness, 
nervousness,  and  mental  cloudiness  are  usually  driven 
away  by  the  increased  ventilation  of  the  body  secured 
by  deep  breathing. 

Care  should  be  taken  that  the  breathing  movements 
are  in  no  way  interfered  with  by  the  clothing.  Corsets 
or  tight  belts  are  likely  to  restrict  the  action  of  the  rib 


THE  LARYNX. 

A  and  a,  the  vocal  cords  in  resting  position ;  B  and  b,  the  vocal  cords  in  position 

for  producing  voice. 

muscles  and  so  tie  the  handles  of  nature's  bellows,  the 
lungs. 

The  vocal  cords  are,  as  we  have  seen,  situated  in 
the  larynx,  at  the  entrance  to  the  windpipe.  "Adam's 
The  apple"  will  show  you  just  where  the  larynx 

voice.  js  located.  Within  the  larynx  are  two  bands 
of  tissue  which  run  across  the  side  walls  from  the 
front  to  the  back.  When  the  vocal  cords  are  brought 


THE   BREATH  -OF  LIFE  135 

together  and  air  is  forced  through  them,  sound  is 
produced.  The  pitch  of  the  voice  depends  upon  the 
weight,  length,  and  tightness  of  the  cords.  Change  of 
pitch  is  brought  about  by  the  tightening  or  loosen- 
ing of  the  vocal  cords.  In  a  stringed  instrument, 
such  as  a  violin,  a  heavy  string  gives  a  lower  tone 
than  a  light  one.  In  strings  that  are  the  same  weight, 
a  short  string  gives  a  higher  tone  than  a  long  one, 
and,  in  those  of  the  same  weight  and  length,  a  tight 
string  gives  a  higher  tone  than  a  loose  one.  In  like 
manner  when  the  vocal  cords  are  long  and  loosely 
stretched  the  voice  is  low  in  pitch.  When  the  cords 
are  short  or  tightly  stretched  the  pitch  is  high. 

A  grown  person  has  a  larger  larynx  and  hence  longer 
vocal  cords  than  a  child,  and  consequently  a  voice  of 
lower  pitch.  The  change  of  voice  in  a  boy  between 
the  ages  of  fourteen  and  eighteen  is  due  to  the  enlarge- 
ment of  the  larynx,  which  takes  place  especially  at 
that  period.  Do  you  think  the  voice  should  be  given 
severe  use  while  it  is  changing  ?  A  man  has  a  larger 
larynx  than  a  woman  and  hence  a  voice  of  lower  pitch. 
When  men  and  women  are  singing  together  the  voices 
of  the  men  are  an  octave  lower  than  those  of  the 
women. 

Speech  is  produced  by  modifying  the  voice  by  means 
of  the  tongue,  teeth,  lips,  and  throat.  In  whispering,' 
the  usual  movements  of  the  mouth  are  made,  but  the 
vocal  cords  are  not  used. 

An  important  means  of  preserving  the  voice  is  to 


136  THE   BODY  IN  HEALTH 

avoid  taking  cold.  If  a  cold  has  been  taken,  the  voice 
should  not  be  used  in  singing  or  loud  speaking  until 
the  hoarseness  is  relieved.  Permanent  injury  to  the 
voice  sometimes  results  from  disregarding  this  rule. 
The  use  of  rich  foods  and  irritating  condiments  in- 
jures the  voice,  by  producing  a  congestion  or  chronic 
inflammation  of  the  throat.  Smokers  are  especially 
liable  to  disease  of  the  throat  on  account  of  the  hot, 
irritating  smoke  brought  into  contact  with  the  delicate 
vocal  cords. 

In  speaking,  and  especially  in  singing,  the  muscles 
of  the  waist  should  be  used.  Increased  force  as  well 
as  greater  volume  may  be  given  to  the  voice  by  the 
use  of  the  abdominal  muscles,  and  the  voice  will  then 
be  much  less  easily  fatigued.  A  high-pitched,  strained 
voice  should  be  avoided,  as  it  is  irritating  to  the  throat, 
tiring  to  the  speaker,  and  disagreeable  to  the  hearer. 
Those  who  have  not  learned  the  use  of  the  abdominal 
muscles  in  speaking  or  singing,  habitually  use  the 
muscles  of  the  throat  and  upper  part  of  the  chest  in 
a  strained  way  during  loud  speaking  and  singing 
greatly  to  their  injury.  You  should  cultivate  full 
tones,  using  the  muscles  of  the  waist  instead  of  the 
upper  part  of  the  chest.  See  if  you  can  tell  what 
muscles  you  usually  use  in  speaking  and  singing. 

HEALTH  PROBLEMS 

i.  Do  the  various  groups  of  workers  in  the  community  in  which 
you  live  exchange  their  products  with  one  another  ?  Suppose 


THE   BREATH  OF  LIFE  137 

there  were  no  such  exchange;  what  would  happen  in  your  com- 
munity ?  Would  something  of  the  same  thing  happen  if 
there  were  no  exchange  among  the  different  cell  groups  in  the 
body  ? 

2.  Point  out  where  your  larynx,  your  trachea,  your  "Adam's 
apple"  are  situated. 

3.  Show  what  happens  to  a  breath  of  air,  taking  it  from  the 
very  start  and  following  it  until  it  comes  out  of  the  body.     Tell 
the  organs  that  it  passes  in  the  body,  the  things  that  it  does  in  the 
body,  and  the  changes  that  come  to  it. 

4.  Have  you  ever  had  a  bit  of  food  go  down  your  windpipe  a 
little  way  ?     Describe  your  experience  when  this  happened. 

5.  What  arrangement  has  nature  provided  so  that  if  food  goes 
the  wrong  way  the  body  will  try  to  throw  it  out.     Will  the  body 
do  this  without  your  directing  it  ?     Why  ? 

6.  Feel  your  lungs  when  you  are  breathing  deeply  and  tell  how 
it  is  possible  for  them  to  expand  as  they  do  and  then  contract. 
Are  there  2000  square  feet  in  the  floor  of  the  room  in  which  you  are 
now  ?     Can  you  imagine  that  the  membrane  in  the  lungs  would 
cover  2000  square  feet  ? 

7.  Why  is  there  so  much  mucus  when  you  have  a  "cold"  ? 
Why  does  the  nose  run  so  freely  when  one  is  breathing  a  good  deal 
of  dust  ? 

8.  Can  you  tell  your  veins  from  your  arteries  by  their  color  ? 
If  so,  describe  the  difference  in  color. 

9.  See  if  you  can  bring  to  school  some  device  that  acts  like  a 
piston  and  show  just  how  it  works.     Show  that  air  is  sucked  in 
when  the  piston  is  moved. 

10.  Explain   coughing;     how   does   it   differ  from  breathing? 
What   is    a   hiccough  ?     What   is   yawning  ?     What   is    sighing  ? 
Sobbing  ?     How  does  laughing  differ  from  regular  breathing  ? 

11.  See  if  you  can  tell  with  what  part  of  your  lungs  you  habit- 
ually breathe.      If  you  try,   can  you   breathe   with   the   entire 
lungs  ? 


138  THE   BODY   IN   HEALTH 

12.  Suggest  some  good  exercise  to  strengthen  the  abdominal 
muscles. 

13.  What  does  it  mean  to  knead  the  stomach?     Why  is  it 
proper  to  speak  of  the  action  of  the  diaphragm  as  kneading  the 
contents  of  the  stomach  ? 

14.  Do  you  think  you  could  permanently  prevent  yourself  from 
breathing  by  effort  of  will  ?     Why  ? 

15.  Explain  why  the  voice  of  a  boy  of  fourteen  or  fifteen 
changes. 

REVIEW  QUESTIONS 

1.  What  is  the  meaning  of  the  "breath  of  life"  ? 

2.  What  is  the  great  purpose  of  breathing  ? 

3.  How  do  the  cells  packed  far  away  in  the  body  get  their 
oxygen  ? 

4.  What  is  meant  by  "division  of  labor"  among  the  cell  groups 
in  the  body  ? 

5.  What  is  the  means  of  communication  between  the  lungs  and 
the  cells  throughout  the  body  ? 

6.  What  is  the  use  of  oxygen  in  the  body  ?     How  does  it  get 
through  the  lungs  into  the  body  ? 

7.  Describe  the  breathing  apparatus,  telling  about  the  parts 
and  their  uses. 

8.  How  much  space  would  the  membrane  in  the  lungs  cover  if 
it  were  spread  out  on  a  flat  surface  ? 

9.  What  is  meant  by  air  passages  ? 

10.  Where   are    the   tonsils   located  ?     What   are   their   uses  ? 
What  may  happen  when  they  become  swollen  and  diseased  ? 

11.  Why  do  people  sometimes  have  tonsils  cut  out  from  their 
throats  ? 

12.  How  has  nature  arranged  it  so  that  the  air  we  breathe  goes 
to  the  lungs  and  the  food  goes  down  the  esophagus  to  the  stomach  ? 

13.  With  what  is  the  breathing  apparatus  lined?     How  does 
this  lining  assist  in  keeping  good  health  ? 


THE   BREATH  OF  LIFE  139 

14.  What  are  the  cilia,  and  what  do  they  do  to  help  the  body 
keep  in  health  ? 

15.  What  happens  to  the  color  of  the  blood  as  it  passes  through 
the  lungs  ?     Through  the  capillaries  ? 

1 6.  Where  does   the  carbon  dioxide  which  escapes  from    the 
lungs  come  from  ? 

17.  What  is  the  color  of  the  blood  in  the  arteries?     In  the 
veins  ?     Explain. 

1 8.  How  are  the  lungs  ventilated  ? 

19.  Describe  the  cavity  in  which  the  lungs  are  placed. 

20.  How  does  the  diaphragm  act  so  as  to  help  one  to  breathe  ? 

21.  What  is  the  meaning  of  inspiration?     Expiration? 

22.  To  what  can  one  liken  the  act  of  breathing  ?     Why  ? 

23.  Why  is  there  a  movement  of  the  entire  lungs  when  one 
breathes  correctly  ? 

24.  What  is  the  reason  why  some  people  breathe  through  the 
mouth  ? 

25.  What  is  the  effect  upon  one's  health  and  mind  of  breathing 
through  the  mouth  ? 

26.  What  should  be  done  for  one  whose  air  passages  are  stopped 
up  with  adenoids  ?     Why  ? 

27.  How  does  breathing  assist  digestion  ? 

28.  Does  one  breathe  as  heavily  or  rapidly  during  sleep  as 
when  he  is  awake  ?     Why  ? 

29.  What  is  the  effect  of  alcohol  upon  the  lungs  ? 

30.  Why  is  it  desirable  to  have  large  lung  capacity  ? 

31.  Mention  ways  in  which  it  is  possible  to  enlarge  the  lung 
capacity.     What  is  said  about  the  value  of  running,  swimming, 
the  daily  cold  bath,  and  so  on,  in  developing  lung  capacity  ? 

32.  Suppose  one  does  not  stretch  his  lungs  to  their  full  capacity 
quite  frequently,  what  may  happen  to  them? 

33.  Where  are  the  vocal  cords  located  ?     Describe  them. 

34.  What  is  the  difference  between  the  vocal  cords  of  a  grown 
person  and  those  of  a  child  ? 


i4o  THE   BODY   IN   HEALTH 

35.  How  is  speech  possible  ? 

36.  How  is  it  possible  to  change  the  pitch  in  one's  voice  ? 

37.  What  may  happen  if  one  strains  the  voice  while  he  is 
hoarse  ? 

38.  What  muscle  should  be  used  especially  in  speaking  and 
singing  ? 


CHAPTER  VIII 
How  THE  BODY  CLEANSES  ITSELF 

IN  a  community  of  people  living  together,  there  is 
always  a  certain  amount  of  waste  matter  to  be  disposed 
of.     In  a  well-regulated  city  the  garbage  or  organs  of 
waste  is  daily  removed  from  the  houses  and  excretion. 
other  offensive  waste  matters   are   carried   away   by 
means  of  sewers.     If  wastes  are  not  promptly  removed, 
but  allowed  to  accumulate,  the  health  of  the  people 
will  be  in  danger. 

We  have  found  that  the  cells  that  make  up  the  body 
community  not  only  take  in  food  and  oxygen,  but 
they  also  send  out  waste  matters  into  the  lymph  that 
surrounds  them.  Of  course,  the  health  of  the  cells 
depends  upon  the  prompt  removal  of  these  wastes. 
The  work  of  sending  them  out  of  the  body  is  called 
excretion,  and  the  cell  groups  that  do  the  work  are 
called  the  organs  of  excretion  or  elimination. 

There  are  four  organs  by  means  of  which  waste  and 
poisonous  matters  are  got  out  of  the  body.  Two  of 
these  we  have  already  considered  :  the  intestine,  which 
removes  the  indigestible  parts  of  food  and  some  wastes 
from  the  digestive  organs  ;  and  the  lungs,  which  carry 

I4T 


142 


THE   BODY  IN  HEALTH 


off  the   carbon   dioxide.     The  other  two  organs   are 

the  kidneys  and  the  skin. 

When  fuel  is  burned  in  a  stove,  the  greater  part  of 

it  passes  off  up  the  chimney  in  the  form  of  gas  and 

smoke,  but  a  small  portion  remains  behind  in  the  form 

of  ashes.  The  same  thing 
takes  place  when  food  is 
burned  in  the  body.  Fats 
and  carbohydrates  are 
changed  by  burning  into 
gaseous  poison  (carbon 
dioxide)  and  water.  The 
gaseous  poison  escapes 
through  the  lungs,  which 
are  the  chimney  of  the 
body,  and  each  of  the 
organs  of  excretion  carry 
off  some  of  the  water. 
Water  is  constantly  being 

THE  KIDNEYS    PLAY   AN  IMPORTANT  PART         given     off     from     the 


,N    R,DD,NC   THE    BODY   OF   WASTES. 


I,  kidney  ;  2  renal  artery;  3,  renal  ar- 
tery;  4,  descending  aorta;  5,  ascend- 
ing vena  cava  ;  6,  ureter. 


Q    tg       reat 
be    Seen    OUt    of    doors    On 

a   cold    day;    and   when 

the  body  is  overheated  the  perspiration  becomes 
visible  upon  the  skin.  A  certain  -amount  of  water 
also  passes  off  through  the  intestine.  The  kidneys 
are,  however,  the  chief  means  of  removing  any  excess 
of  water  from  the  blood.  The  combustion  of  proteid 


HOW  THE   BODY  CLEANSES   ITSELF       143 


foods  produces,  besides  carbon  dioxide  and  water,  a 
certain  amount  of  wastes,  which  correspond  to  the 
ashes  that  are  left  behind  when  the  food  is  burned  in 
the  stove.  These  wastes,  after  being  prepared  and 
made  soluble,  are  extracted  from  the  blood  and  sent 
out  of  the  body  by  the  kidneys.  A  small  amount  of 
both  the  gase- 
ous poison  and 
other  wastes 
passes  out 
through  the 
skin  in  the 
perspiration. 

These  im- 
portant organs 
of  excretion 
are  located  at 
the  back  part 
of  the  abdom- 
inal cavity, 
just  below  the 
lower  ribs. 
They  are  placed  close  to  the  spinal  column,  one  on  each 
side.  Each  kidney  is  a  gland  shaped  like  a  kidney 
bean,  and  weighs  from  four  to  six  ounces. 

Examined  under  the  microscope,  the  substance  of 
the  kidney  is  found  to  be  made  up  of  very  delicate 
tubes,  which  begin  near  the  surface  of  the  organ  in 
delicate  little  round  sacs.  Each  sac  contains  a 


WITHOUT   THESE    ORGANS    or    EXCRETION    THE   'BODY 

WOULD    BE    COMPLETELY    POISONED    IN   A    FEW   HOURS. 


144 


THE   BODY  IN  HEALTH 


minute  blood  vessel  coiled  up.  These  tubes  combine 
as  they  pass  towards  the  center,  becoming  larger  in 
size  and  finally  opening  into  a  cavity  in  the  kidney. 
This  cavity  communicates  with  a  long  tube,  called 

the  bladder,  from  which 
it  is  discharged  from  time 
to  time.  The  kidney  ex- 
cretion (the  urine)  con- 
tains some  of  the  most 
poisonous  waste  elements 
of  the  body.  When  from 
any  cause  the  action  of 
the  kidneys  ceases,  death 
soon  takes  place. 

The  kidneys  are  always 
at  work,  but  are  more 
active  at  some  times  than 
at  others.  Anything  that 
increases  the  flow  of  blood 
through  the  kidneys  stim- 
ulates them  to  greater  ac- 
tivity. Drinking  freely 
of  water  is  beneficial  to 
the  kidneys.  It  dissolves  the  poisons  and  aids  the 
kidneys  in  removing  them.  In  summer,  especially, 
when  a  large  amount  of  water  passes  off  through 
the  skin  in  the  perspiration,  it  is  very  necessary  to 
drink  a  sufficient  amount  of  water  to  make  good  the 
loss  from  this  source. 


A  CROSS-SECTION  OF  THE  KIDNEY.  No- 
TICE  THAT  THE  SUBSTANCE  OF  THE 
KIDNEY  IS  MADE  UP  OF  DELICATE 
TUBES  WHICH  COMBINE  AS  THEY  PASS 
TOWARD  THE  CENTER. 

I,  ureter;  2,  cortex;  3,  capsule;  4,  tu- 
bule; 5,  renal  corpuscle;  6,  fat;  7, 
pyramid ;  8,  blood  vessel. 


HOW  THE   BODY  CLEANSES   ITSELF       145 

Overeating,   especially  of  protein  foods,  the  waste 
products  of  which  it  is  the  business  of  the  kidneys  to 
remove,  increases  the  work  of  the  kidneys, 
and  is  likely  to  overtax  them.     The  kidneys  that 
are  in  close  sympathy  with  the  skin.     Both  ^ure  ^e 
remove  from   the   blood   water   and   wastes. 
Whatever  interferes  with  the  work  of  the  one  will  im- 
pose extra  labor  upon  the  other.     Sedentary  habits, 
neglect  of  bathing,  exposure  to  severe  cold,  and  ex- 
cessive use  of  flesh  foods  may  be   mentioned   as  the 
chief  causes   of  kidney   diseases,    which    are   rapidly 
increasing  in  our  country. 

Alcohol  injures  the  kidneys,  as  it  does  the  liver 
and  all  other  parts  of  the  body  with  which  it  comes 
in  direct  contact.  It  causes  inflammations  and  changes 
which  finally  result  in  the  disease  and  decay  of  the 
organs.  Disease  of  the  kidneys  is  very  frequent 
among  beer  drinkers.  The  free  use  of  ale  and  beer 
excites  the  kidneys  to  excessive  action  until  they 
become  worn  out. 

It  is  a  part  of  the  work  of  the  kidneys  to  remove 
from  the  blood  poisonous  substances  formed  in  the 
stomach  and  intestines  as  the  result  of  indigestion, 
and  to  carry  out  of  the  system  food  substances  which 
have  been  taken  into  the  blood  without  being  perfectly 
digested.  The  liver,  as  we  have  seen,  completes  the 
work  .of  digestion.  When  it  becomes  disabled  by  the 
use  of  alcohol,  some  portions  of  the  food  are  allowed 
to  pass  into  the  general  circulation  without  having 


146  THE   BODY  IN  HEALTH 

been  so  changed  by  the  liver  that  they  can  be  used 
by  the  cells  in  building  up  the  body.  The  removal  of 
these  useless  substances  adds  greatly  to  the  work  of  the 
kidneys. 

We  see,  then,  what  a  chain  of  mischief  is  started 
by  the  use  of  alcohol. 

1.  Alcohol   renders   the   stomach   unable   to   digest 
food  properly  and  so  throws  extra  work  upon  the  liver. 

2.  Alcohol  injures  the  liver  so  that  it  cannot  perform 
its  ordinary  duties,  besides  putting  upon  it  the  double 
labor  of  removing  the  alcohol  and  endeavoring  to  com- 
plete the  imperfect  work  done  by  the  stomach. 

3.  The  kidneys  are  not  only  disabled  by  the  alcohol 
but  are  compelled  to  remove  a  portion  of  it  from  the 
body,    as  well   as   the   poisonous   and   unusable   sub- 
stances resulting  from  the  injury  to  the  stomach  and 
liver. 

One  evil  resulting  from  the  use  of  alcohol  creates 
another,  and  so  the  evil  is  multiplied. 

The  chief  purposes  of  the  skin  are:    (i)  To  form  a 
protective  covering:  for  the  body,  in  order  to 

The  skin.  r  ,  CJ,         , 

prevent  the  entrance  or  harmful  substances, 
such  as  germs.  (2)  To  regulate  the  heat  of  the  body, 
keeping  it  at  a  constant  temperature.  (3)  To  receive 
impressions  of  heat,  cold,  pain,  and  §o  on.  (4)  It 
also,  to  a  small  extent,  as  we  have  seen,  assists  the 
lungs  and  the  kidneys  in  the  work  of  excretion. 

You  may  remember  that  this  outer  layer  of  the  skin 
is  called  the  epidermis.     This  is  a  covering  for  the 


HOW  THE   BODY  CLEANSES   ITSELF       147 

dermis,  which  contains  the  active  parts  of  the  skin,  — 
the  glands,  nerves,  and  blood  vessels,  —  by  means 
of  which  the  various  kinds  of  work  of  the  skin  are 
carried  on. 

The  flattened  cells  which  compose  the  outer  layers 
of  the  epidermis  are  all  the  time  drying  and  scaling  off 
and  so  the  skin  needs  to  be  constantly  renewed  by  the 


7 


A    SECTION    OF  THE    OUTER   LAYER   OF  THE    SKIN. 

making  of  new  cells.  We  have  learned  how  the  cells 
multiply,  by  each  cell's  dividing  into  two  new  cells. 
The  cells  in  the  lower  layers  of  the  epidermis  divide 
in  this  way  and  form  new  cells  to  take  the  place  of 
those  that  have  been  thrown  off. 

Since  the  epidermis  has  for  its  purpose  the  protection 
of  the  delicate  parts  beneath  it,  it  is  thickest  in  those 
regions  of  the  body  where  there  is  the  most  pressure. 
On  the  soles  of  the  feet  and  the  palms  of  the  hands 


148  THE   BODY  IN   HEALTH 

there  may  be  as  many  as  one  hundred  layers  of  epider- 
mal cells,  while  on  other  parts  of  the  body  there  are 
not  more  than  twenty.  Constant  pressure  upon  any 
part  of  the  skin  causes  a  great  increase  in  the  number 
of  epidermal  cells  at  that  point.  A  corn  on  the  foot 
is  due  to  the  thickening  of  the  epidermis  resulting 
from  the  pressure  of  the  shoe. 

The  hair  and  nails  are  curious  horny  structures 
which  grow  out  from  the  skin.  Hairs  are  found  upon 
all  parts  of  the  body,  with  the  exception  of  the  palms 
of  the  hands  and  the  soles  of  the  feet.  Each  hair 
grows  from  a  small,  deep  pocket  in  the  skin,  called  the 
hair  follicle.  Both  nails  and  hair  are  constantly  being 
formed  in  the  dermis  and  pushed  upward.  The  uses 
of  the  hair  seem  to  be  to  protect  the  parts  beneath 
from  changes  of  temperature,  as  in  the  case  of  the 
head ;  to  protect  sensitive  parts  from  dust  and  other 
harmful  substances,  as  in  the  eyelashes  and  eyebrows, 
and  the  hairs  of  the  nostrils ;  and  to  aid  the  sense  of 
touch. 

Opening  into  the  hair  follicle  are  one  or  more  seba- 
ceous glands,  which  pour  out  an  oily  substance  to 
moisten  the  hair,  to  lubricate  the  skin,  and  to  protect 
it  from  drying  and  chapping.  The  color  of  the  hair 
is  due  to  pigmented  cells  like  those  which  give  the  skin 
its  color. 

The  nails  grow  from  a  little  fold  in  the  skin  and 
from  the  tissues  over  which  they  lie.  They  protect 
the  ends  of  the  fingers  and  toes,  increase  the  delicacy 


HOW  THE   BODY  CLEANSES   ITSELF       149 


BODY 


LUNULA... 


of  the  sense  of  touch,  and  aid  the  fingers  in  picking  up 
small  objects. 

The  inner  layer  of  the  skin,  the  true  skin  or  dermis, 
contains  many  blood  vessels,  glands,  and  nerves,  and 
also  minute  muscles  connected 
with  the  hairs.  When  one  is  chilly 
these  muscles  sometimes  contract, 
causing  a  rough  appearance  of 
the  skin  commonly  called  "goose 
flesh." 

The  outer  surface  of  the  true 
skin  is  not  flat,  but  is  thrown  up 
into  moundlike  projections  called 
papillae,  which  project  up  into 
the  epidermis.  Some  of  the  pa- 
pillae contain  blood  vessels  and  some  of  the  nerve 
endings  of  the  sense  of  touch.  The  large  number  of 
blood  vessels  with  which  it  is  provided  give  the  skin 
such  vitality  that  small  wounds  in  it  will  heal  very 
rapidly,  if  one's  blood  is  healthy.  Even  when  quite  a 
large  surface  of  the  skin  is  removed,  new  skin  will  grow 
out  from  the  edges  until  the  gap  is  entirely  covered. 

It  is  very  important  that  the  skin,  being  the  pro- 
tective covering  of  the  body,  should  be  kept  from 
injury.  Even  a  small  opening  in  the  skin,  such  as  a 
slight  scratch,  may  open  up  a  way  for  a  deadly  germ, 
which  may  cause  serious  and  even  fatal  results.  Of 
course,  wounds  in  the  skin  should  be  cleansed  with  a 
disinfecting  fluid  and  kept  covered. 


THE      PROPER     CARE      OF    A 
NAIL. 


150 


THE   BODY  IN  HEALTH 


The  work  of  the  sweat  glands,  of  which  there  are 
in  the  skin  not  less  than  two  and  one  half  millions,  is 
to  cool  the  body  by  pouring  out  water  upon  the  skin. 
This  they  are  doing  constantly,  but  the  amount  of 
water  is  usually  too  small  to  be  noticeable.  It  evapo- 
rates before  it  becomes  visible  and  so  is  called  insensible 
perspiration.  The  amount  of  insensible  perspiration 
produced  daily  by  the  entire  skin  is  usually  from  one 
and  one  half  to  four  pints.  It  is  by  the  evaporation 
of  the  perspiration  that  the  body  is  cooled.  Exercise 
or  heat  greatly  increases  the  amount  of  perspiration  so 
that  it  becomes  visible  upon  the  skin  and  is  known  as 
.  sensible  perspiration. 


While  the 
tion  is   not  really  an 

excretion,  but  a  heat- 
regulating  secretion,  it 
is  at  the  same  time  a 
means  by  which  some 
of  the  waste  matter 
contained  hi  the  blood 
is  carried  out  of  the 
body.  Around  the  lower  part  of  a  sweat  gland  are 
many  blood  capillaries  from  which  an  abundant  supply 
of  lymph  escapes.  We  have  found  that  lymph  con- 
tains gaseous  poisons  and  other  waste  substances 
discharged  into  it  by  the  cells.  When  the  water  of 
the  lymph  passes  through  the  walls  of  the  sweat  glands, 
it  carries  with  it  a  small  quantity  of  these  wastes, 


THE    SWEAT   OR   PERSPIRATION   GLANDS. 


HOW  THE   BODY  CLEANSES   ITSELF       151 

which  are  thus  discharged  from  the  sweat  gland   in 
the  perspiration. 

When  the  water  evaporates  from  the  surface  of  the 
body,  the  waste  matter  it  contains  remains  on  the  skin 
and  becomes  mixed  with  oil  from  the  sebaceous  glands, 
dead  epidermis,  and  dust  from  the  air  and  the  clothing. 
If  this  is  not  regularly  removed  by  bathing  and  friction 
of  the  skin,  it  will  form  a  thin  coating  all  over  the  body, 
and  will  give  off  a  bad  odor  and  interfere  with  the 
work  of  the  skin.  Where  there  is  dirt,  there  are  germs. 
An  unclean  condition  of  the  skin  encourages  the  growth 
of  germs  upon  it,  and  some  of  them  may  get  down  into 
the  hair  follicles  and  the  sebaceous  glands,  and  cause 
pimples  and  other  skin  eruptions. 

HEALTH  PROBLEMS 

1.  How  are  the  various  wastes  in  your  community  got  rid  of? 
Are  there  as  many  groups  of  persons  attending  to  this  work  in 
your  community  as  there  are  groups  of  cells  attending  to  similar 
work  in  your  body  ? 

2.  Suppose  any  group  of  persons  in  your  community  who  re- 
move wastes  should  cease  to  do  their  work,  what  would  happen  to 
the  people  ?     Such  things  often  happen  in  communities ;    have 
you  ever  known  of  such  a  case  ? 

3.  Show  that  the  burning  of  food  in  the  body  leaves  something 
like  the  ashes  left  from  the  burning  of  wood  in  a  stove.     Suppose 
the  ashes  in  a  stove  or  a  furnace  should  not  be  removed  at  all. 
What  would  happen  in  time  to  the  fire  ?     Is  it  the  same  in  the 
body  ? 

4.  Do  you  know  whether  people  who  eat  a  great  deal  of  meat 
and  live  a  sedentary  life  are  troubled  with  kidney  diseases  ?     Ask 


i$2  THE   BODY  IN  HEALTH 

your  physician  this  question.  If  he  tells  you  that  such  people  are 
likely  to  have  kidney  diseases,  ask  him  why  and  remember  what 
he  says. 

5.  Ask  a  physician  the  same  question  in  regard  to  people  who 
drink  a  good  deal  of  wine,  beer,  or  whisky,  and  be  careful  to  get 
exactly  what  the  physician  says. 

6.  Suppose  a  person  who  lives  indoors  should  eat  three  meals  a 
day  composed  largely  of  beans,  cheese,  lean  meat,  milk,  and  eggs. 
Should  you  expect  such  a  person  to  keep  well  ?     Explain. 

7.  Suppose  the  liver  and  the  kidneys  could  express  their  feelings 
when  a  man  was  about  to  take  a  glass  of  whisky,  what  do  you 
think  they  would  say,  and  why  ? 

8.  Enumerate  the  different  ways  in  which  one  may  illtreat  his 
kidneys.     Do  you  think  they  should  be  treated  as  friends  rather 
than  as  slaves  ?     Why  ? 

9.  What  is  the  greatest  enemy  which  the  body  has  ?     Be  pre- 
pared to  give  reasons  for  your  opinion. 

10.  Suppose  you  should  cover  the  surface  of  your  body  with 
wax,  what  do  you  think  would  happen  ?     Would  it  be  about  the 
same  if  you  should  let  the  body  be  covered  over  with  the  wastes 
thrown  out  by  the  skin  ? 

11.  Why  is  there  no  hair  on  the  palms  of  one's  hands  or  the 
soles  of  his  feet  ?     Do  you  think  the  hairs  on  the  back  of  the  hand 
are  of  any  use  to  the  body  ? 

12.  Explain  how  it  is  possible  for  one  after  a  hot  foot  bath  to 
rub  off  considerable  of  the  outer  skin  of  the  feet.     Why  is  there  so 
much  of  this  skin  on  the  feet  ? 

13.  Think  of  some  way  to  show  that  the  sebaceous  glands  con- 
tain an  oil  which  they  pour  out  to  keep  the  skin. from  becoming 
hard  and  dry. 

14.  Why  is  it  that  people  who  live  in  hot  countries  where  there 
is  a  great  deal  of  sunshine  have  black  hair,  while  people  who  live 
in  northern  countries  where  there  is  not  so  much  sunshine  have 
lighter  colored  hair  ? 


HOW  THE   BODY  CLEANSES   ITSELF       153 

15.  Have  you  known  of  any  fatal  diseases  to  be  due  to  injury 
to  the  skin  ?     If  so,  describe  them,  and  say  whether  with  right 
treatment  the  victims  could  have  been  saved. 

1 6.  Think  of  some  way  to  show  that  there  is  invisible  perspira- 
tion pouring  out  from  the  skin  all  the  time. 

17.  What  is  the  best  way  to  take  a  warm  bath?     Mention 
injurious  ways  of  taking  baths  which  are  sometimes  adopted   by 
people. 

REVIEW  QUESTIONS 

I.-  What  name  is  given  to  the  work  of  sending  wastes  out  of  the 
body  ?     To  the  organs  which  have  charge  of  getting  rid  of  wastes  ? 

2.  What  are  the  wastes  formed  by  the  burning  of  food  in  the 
body  ? 

3.  How  is  the  gaseous  poison,  carbon  dioxide,  got  out  of  the 
body  ? 

4.  What  waste  does  the  skin  take  out  of  the  body  ?     What 
the  kidneys  ? 

5.  Where  are  the  kidneys  located  ?     What  is  their  shape  ? 

6.  Describe  what  one  sees  when  he  looks  at  the  substance  of  the 
kidneys  through  a  microscope. 

7.  What  happens  when  the  kidneys  cease  to  do  their  work  ? 

8.  What  will  increase  the  action  of  the  kidneys  ? 

9.  Suppose  the  skin  does  not  do  its  work.     What  is  the  effect 
on  the  kidneys  ?     Why  ? 

10.  What   effect   do   the  following   have   upon   the   kidneys : 
over-eating  (especially  protein  foods) ;    the  skin's  failing  to  do  its 
work;    severe  cold;    neglect  of  bathing;    sedentary  habits;    and 
using  alcohol. 

11.  When  the  food  is  not  digested  properly,  do  the  kidneys 
suffer?    Why? 

12.  Give  the  "chain  of  mischief"  started  by  the  use  of  alcohol. 

13.  Name  the  four  chief  purposes  of  the  skin. 

14.  What  is  the  outer  skin  called,  and  what  is  its  use  ?     What 
is  the  inner  skin  called,  and  what  is  its  use  ? 


I54  THE   BODY  IN  HEALTH 

15.  What  happens  to  the  epidermis  when  it  is  rubbed  by  the 
shoes,  for  instance  ? 

16.  What  is  the  connection  between  the  hair  and  nails  and  the 
epidermis  ?    What  is  the  name  of  the  pockets  in  the  skin  from 
which  the  hair  grows  ? 

17.  What  is  the  use  of  the  sebaceous  glands  ? 

1 8.  What  are  the  papillae  ?    To  what  use  are  they  put  ? 

19.  Why  is  it  necessary  to  be  careful  not  to  injure  the  skin  ? 

20.  How  should  wounds  in  the  skin  be  cared  for  ? 

21.  What  is  the  work  of  the  sweat  glands  ? 

22.  What  is  the  meaning  of  insensible  perspiration  ?     Of  sen- 
sible perspiration  ? 

23.  When  water  evaporates  from  the  surface  of  the  skin,  what 
does  it  leave  behind  ? 

24.  Why  is  it  necessary  to  bathe  frequently  ? 


CHAPTER  IX 
How  THE  TEMPERATURE  OF  THE  BODY  is  REGULATED 

WHETHER  we  are  shivering  with  cold  in  the  winter 
or  perspiring  in  the  warmest  weather,  a  physician's 
thermometer  placed  in  the  mouth  will  show  xhetem- 
that  the  temperature  of  the  body  inside  is  perature  of 
exactly  the  same  at  both  times.  The  power  thebody- 
to  maintain  a  certain  temperature  under  all  the  differ- 
ent conditions  of  life  is  one  of  the  most  remarkable 
of  the  powers  of  the  human  body.  The  internal  tem- 
perature of  the  body  is  constantly  maintained  at  about 
98^  degrees  F.  At  all  seasons  and  in  all  countries  the 
variation  in  temperature  when  one  is  in  health  is 
scarcely  more  than  one  degree.  This  is  more  wonderful 
when  we  consider  how  greatly  the  temperature  of  the 
air  may  vary  at  different  seasons  and  in  different 
countries, — from  70  degrees  below  zero  in  Arctic  regions 
to  130  degrees  above  in  the  sultry  deserts  of  northern 
Africa. 

Things  without  life,  such  as  a  stone  or  a  piece  of 
earth,  usually  have  the  temperature  of  the  surrounding 
air.  Many  living  creatures  do  the  same  thing.  The 
temperature  of  a  frog,  a  snake,  a  turtle,  or  an  earth- 
worm differs  little  from  that  of  its  surroundings. 


156  THE   BODY  IN  HEALTH 

The  only  creatures  which  have  this  great  power  of 
maintaining  a  constant  temperature  in  spite  of  changes 
in  the  surrounding  air  are  mammals  and  birds.  These 
animals  are  called  warm-blooded,  because  they  are 
usually  warmer  than  surrounding  objects  ;  and  animals 
that  have  not  this  power  are  called  cold-blooded,  be- 
cause they  usually  feel  colder  to  the  touch  than  do 
warm-blooded  animals. 

As  we  have  already  learned,  the  heat  of  the  body  is 
produced  by  a  slow  combustion  of  food  ;  and  this  is 
taking  place  all  the  time.  This  combustion  goes  on 
chiefly  in  the  muscles  and  is  much  more  active  during 
exercise  than  when  the  body  is  at  rest.  Yet  the  in- 
ternal temperature  of  the  body  during  rest  and  moder- 
ate exercise  is  the  same,  although  much  more  heat  is 
produced  during  exercise.  The  loss  of  heat  from  the 
body  takes  place  chiefly  at  the  surface,  through  the 
skin.  A  great  deal  more  heat  is  lost  from  the  body 
when  the  surrounding  air  is  cold,  yet  the  body  temper- 
ature remains  the  same.  By  what  wonderful  means  is 
the  body  temperature  so  perfectly  arranged  that  it 
remains  the  same  under  all  these  different  conditions  ? 

Think  of  two  ways  in  which  you  may  regulate  the 
temperature  of  a  room.  If  the  room  becomes  too 
How  the  warm>  y°u  open  a  window  or  door  to  let 
body  tem-  some  of  the  heat  escape.  If  the  room  is  too 
peratureis  co\d  you  poke  up  the  fire,  put  on  more  fuel, 

regulated. 

or  open  up  the  stove  draughts  so  that  more 
heat  will  be  produced.     You  may  control  the  tempera- 


REGULATING  BODY  TEMPERATURE       157 

ture  of  a  room  by  regulating  the  amount  of  heat  that  is 
produced  or  by  regulating  the  amount  of  heat  that 


IF  THE    ROOM    IS   TOO   WARM  YOU    OPEN   THE   WINDOW  TO    LET    SOME    OF  THE 

HEAT    ESCAPE. 

escapes.     The  temperature  of  the  body  is  regulated  in 
the  same  way. 

The  marvelous  work  of  regulating  the  temperature 
of  the  body  is  done,  not  by  one  organ  alone,  but  by 


158  THE   BODY  IN  HEALTH 

several  working  together  under  the  direction  of  the 
nerves.  The  nervous  system  is  the  real  regulator  of 
the  body  temperature,  but  the  work  is  done  by  means 
of  the  three  organs  :  the  muscles,  the  blood  vessels, 
and  the  sweat  glands. 

The  process  of  heat-making  which  is  carried  on  in 
the  muscles  is  regulated  by  certain  nerve  centers  in  the 
brain  and  spinal  cord,  which  are  connected  with  the 
muscles  by  nerves,  so  that  the  making  of  heat  is  under 
constant  and  perfect  control.  When  the  body  is  ex- 
posed to  cold  air  or  water  or  is  in  any  way  cooled  so 
that  the  temperature  of  the  blood  is  lowered,  nerve 
centers  in  the  brain  incite  increased  activity  in  the 
heat-making  organs  and  more  fuel  is  burned  in  the 
cells.  In  this  way  the  heat-making  process  is  ad- 
justed to  the  needs  of  the  body. 

When  the  cooling  of  the  body  is  continued  to  such 
a  point  as  to  produce  a  considerable  fall  in  the  tempera- 
ture of  the  blood,  one  usually  feels  chilly  and  begins 
to  shiver.  "Shivering"  consists  in  a  rapid  contraction 
of  the  muscles  in  which  nearly  all  the  muscles  of  the 
body  take  part.  As  muscular  action  is  always  ac- 
companied by  the  making  of  heat,  this  is  an  automatic 
method  of  warming  the  body.  Shivering  is  simply  a 
natural  method  by  which  the  body  is  exercised  in  order 
to  increase  the  amount  of  heat  production. 

The  loss  of  heat  from  the  body  is  chiefly  at  the  sur- 
face, and  the  device  for  controlling  it  is  in  the  skin. 
There  are  two  ways  in  which  the  skin  controls  the 


REGULATING  BODY  TEMPERATURE       159 

escape  of  heat  from  the  body.  One  is  by  regulating 
the  amount  of  blood  that  comes  out  into  the  skin. 
The  blood  carries  the  heat  from  the  warm  interior  of 
the  body  to  the  surface,  where  it  is  cooled  off  in  the 
skin.  The  temperature  of  the  skin  is  always  much 
lower  than  the  internal  temperature  and  seldom  rises 
above  92  degrees  or  93  degrees.  After  cooling,  the  blood 
is  carried  back  to  the  interior  of  the  body.  In  this 
way  the  blood  equalizes  the  body  temperature,  and 
keeps  it  from  becoming  too  hot  in  some  parts  and  not 
warm  enough  in  others. 

When  the  body  is  exposed  to  cold,  the  blood  vessels 
of  the  skin  contract  and  shut  out  the  blood,  allowing 
only  a  small  quantity  to  pass  through.  The  blood 
is  thus  kept  in  the  warm  interior  of  the  body.  When 
the  blood  becomes  too  hot,  the  blood  vessels  of  the 
skin  open  up  and  allow  a  large  amount  of  blood  to  pass 
out  into  the  skin  where  it  becomes  cooled.  This  is 
the  cause  of  the  flushing  of  the  face  and  sometimes 
even  of  the  whole  body,  when  it  is  exposed  to  a  warm 
atmosphere. 

Through  these  changes  in  the  circulation  of  the  blood 
in  the  skin,  the  heat  loss  may  be  increased  to  three  or 
four  times  the  usual  amount  or  lessened  to  the  same 
extent. 

The  other  method  by  which  the  skin  regulates  the 
loss  of  heat  is  by  the  work  of  the  sweat  glands.  We 
have  already  learned  that  the  body  is  cooled  by  the 
evaporation  of  perspiration.  Now  evaporation  cannot 


160  THE   BODY  IN  HEALTH 

take  place  without  heat.  A  liquid  in  evaporating 
must  take  up  heat  from  surrounding  objects.  You 
may  easily  demonstrate  this  by  wetting  one  of  your 
hands  then  holding  both  hands  in  a  current  of  dry  air. 
Why  does  the  wet  hand  become  so  much  cooler  than 
the  dry  one  ?  You  may  make  the  same  experiment 
by  wetting  one  finger  and  noticing  how  much  cooler 
it  becomes  than  the  rest  of  the  hand.  If  alcohol  or 
ether,  which  evaporates  much  more  quickly  than 
water,  is  used,  the  cooling  off  will  be  much  more  marked. 
In  the  evaporation  of  a  pound  of  water  as  much  as  one 
thousand  heat  units  are  absorbed  ;  that  is,  as  much 
heat  is  consumed  in  the  evaporation  of  a  pound  of 
water  as  would  be  required  to  raise  half  a  ton  of  water 
one  degree  in  temperature.  About  two  and  one  half 
pounds  of  water  are  evaporated  from  the  skin  daily, 
representing  a  heat  loss  of  about  two  thousand  five 
hundred  heat  units,  or  one-fourth  of  the  amount  of 
heat  generated  in  the  body.  The  heat  loss  may  be 
greatly  increased  by  exercise  or  exposure  of  the  body 
to  cool  air. 

The  wonderful  power  of  the  sweat  glands  to  protect 
the  body  from  injury  by  excessive  heat  has  been  shown 
by  some  experiments  in  which  men  remained  for  some 
time  in  a  room  heated  to  260  degrees  or  forty-eight 
degrees  above  boiling  point.  Meat  was  being  cooked 
by  the  heated  air  of  the  room,  an  egg  was  roasted 
hard  in  twenty  minutes,  and  water  soon  boiled  ;  but 
the  men,  although  very  uncomfortable,  remained  un- 


REGULATING  BODY  TEMPERATURE       161 

injured,  without  even  a  rise  of  temperature.  The 
two  million  little  sweat  glands  of  the  skin  were  hard 
at  work  all  the  time  to  save  them.  The  evaporation 
of  the  water  which  they  poured  out  upon  the  skin  in 
great  quantities  cooled  the  skin  and  prevented  it 
from  becoming  cooked,  as  it  would  otherwise  have 
been. 

In  order  for  the  evaporation  of  the  sweat  to  take 
place  freely,  the  air  must  be  dry.  Why  ?  In  moist 
air,  when  there  is  little  or  no  evaporation  of  the  sweat, 
there  is  little  cooling  of  the  body  by  this  means.  For 
this  reason,  one  is  much  more  liable  to  suffer  with 
heat  in  a  moist  atmosphere,  on  a  " muggy"  day,  for 
instance,  than  in  a  dry  atmosphere. 

A  small  amount  of  heat  escapes  from  the  body  in 
the  breath  and  by  the  evaporation  of  moisture  from 
the  lungs  and  air  passages.  This  is  why  a  dog,  which 
does  not  sweat,  pants  when  overheated,  either  from 
exercise  or  from  hot  air.  By  the  act  of  panting,  the 
air  is  rapidly  passed  in  and  out  of  the  lungs,  and  the 
increased  evaporation  cools  the  dog's  blood. 

So  constant  must  be  the  body  temperature  in  health 
that  any  variation  from  the  normal,  98^-  +  degrees,  gives 
cause  for  anxiety.  As  a  result  of  some  shock  or  in  one 
who  is  very  feeble,  the  temperature  may  fall  below 
normal,  through  insufficient  heat  production  or  too 
great  an  escape  of  heat.  More  often  there  is  a  rise 
of  temperature  above  the  normal,  and  then  one  is 
said  to  have  a  fever.  In  fevers,  heat  production  and 


162  THE   BODY  IN  HEALTH 

loss  are  not  so  perfectly  controlled  as  in  health,  because 
the  heat  centers  are  disturbed  by  the  poisons  circulating 
in  the  blood.  The  sweat  glands  are  not  so  active  as 
usual,  and  the  surplus  heat  does  not  escape. 

When  one  has  a  fever,  the  temperature  may  be  re- 
duced by  sponging  the  body  with  water,  the  evapora- 
tion of  which  will  carry  off  some  of  the  surplus  heat. 
A  hot  bath  or  pack  may  be  given  to  excite  the  activity 
of  the  sweat  glands. 

The  heat-regulating  functions  of  the  body  are  not 
under  the  control  of  the  will.  One  cannot  start  or 
check  the  perspiration  or  cause  the  surface  blood  vessels 
to  contract  or  dilate  by  an  effort  of  will.  We  may, 
however,  now  that  we  know  how  heat  is  produced  in 
the  body  and  how  it  escapes,  do  various  things  to  in- 
crease or  lessen  heat  production  or  heat  loss. 

By  active  exercise,  for  instance,  we  can  greatly  in- 
crease the  amount  of  heat-  produced.  One  exposed 
Active  to  the  cold  does  not  usually  stand  still.  He 
exercise.  walks  or  runs  about,  stamps  his  feet,  claps 
his  hands,  swings  his  arms,  and  engages  in  all  sorts  of 
muscular  activities  that  increase  heat  production.  In 
very  warm  weather,  one  is,  on  the  other  hand,  much 
less  active.  In  the  warm  countries,  the  hottest  part 
of  the  day  is  usually  passed  in  sleep,  reducing  as 
much  as  possible  the  amount  of  heat  production. 

Heat  production  is  also  determined  by  the  quantity 
and  quality  of  the  food.  In  the  Arctic  regions,  men 
live  largely  on  fat,  which  has  the  highest  heat  value  of 


REGULATING   BODY  TEMPERATURE       163 

any  food,  while  men  of  the  tropics  live  largely  on  rice, 
and  fruits,  which  have  a  low  heat  value.  A  larger 
quantity  of  food  is  required  in  the  winter  than  in  the 
summer,  especially  by  one  actively  exercising  out  of 
doors.  Why,  do  you  think  ? 

The  escape  of  heat  from  the  body  in  cold  climates 
is  greatly  lessened  by  the  custom  of  living  in  heated 
houses.     Some     animals     burrow     into     the  Living  in 
ground  and  make  themselves  nests  in  which  heated 
to   pass   the  winter.     No   animal   but    man,  homes- 
however,    provides    itself   with    artificial    heat.     This 
practice  has  many  advantages,  but  it  also  has  some 
disadvantages.     What  are  they  ? 

Do  you  think  there  is  any  danger  from  overheated 
rooms  ?  Have  you  noticed  that  one  is  very  likely  to 
take  cold  in  passing  from  a  hot  room  into  the  cold 
outdoor  air  ?  Explain.  Overheated  rooms  also  have 
a  weakening  effect  upon  the  system.  The  skin  becomes 
relaxed,  and  the  body  more  sensitive  to  cold.  The 
heat-making  powers  in  people  who  live  in  very  hot 
rooms  or  houses  are  likely  to  lose  some  of  their  vigor, 
for  lack  of  exercise. 

Cold  rooms,  or  rooms  insufficiently  heated,  may 
also  have  injurious  effects  because  too  much  heat  may 
be  lost  from  the  body.  When  the  body  is  chilled,  and 
the  surface  blood  vessels  contract,  the  blood  is  forced 
in  upon  the  organs  within  and  these  are  liable  to  be- 
come congested. 

The  best  room  temperature  is  68  degrees  F.     The 


164  THE   BODY   IN  HEALTH 

circulation  of  the  blood  will  then  be  well  balanced. 
There  will  be  no  excess  of  blood  in  the  skin  or  in  the 
internal  organs,  but  it  will  be  properly  distributed 
between  them. 

When  the  skin  is  heated  from  exercise  or  a  hot 
atmosphere,  the  blood  vessels  it  contains  become  filled 
Colds  with  the  blood  that  is  forced  into  them.  If 
their  cause  a  person  in  this  condition,  covered  with 
and  cure,  perspiration,  sits  in  a  draught  or  a  cool  place, 
the  blood  vessels  in  the  skin  will  contract  and  the 
blood  will  be  forced  inward.  Some  part  of  the  lining 
membrane  of  the  body,  usually  the  nose,  throat,  or 
lungs,  will  be  liable  to  become  congested  with  blood, 
and  a  cold  will  be  the  result.  The  white  cells  in  the 
congested  blood  vessels  will  lose  their  vigor  and  be- 
come inactive,  and  the  microbes  may  get  the  upper 
hand  and  make  mischief.  For  this  reason,  a  person 
who  has  a  cold  is  likely  to  take  other  diseases  to  which 
he  is  exposed. 

The  best  thing  to  do  when  a  cold  is  coming  on  is  to 
increase  the  activity  of  the  skin  as  much  as  possible. 
This  may  be  done  in  several  ways :  (i)  By  vigorous 
exercise  which  will  bring  every  sweat  gland  into  activity ; 

(2)  by  a  hot  foot  bath  or  a  full  bath,  which  will  expand 
the  surface  vessels  and  bring  the  blood  to  the  skin ; 

(3)  by  drinking  freely  of  hot  water  or  hot  lemonade, 
which  will  aid  in  starting  a  good  perspiration. 

When  the  blood  is  drawn  to  the  surface  of  the  body, 
the  delicate  internal  organs  are  relieved  of  the  excess 


REGULATING   BODY  TEMPERATURE       165 

of   superfluous  blood  that  causes  the  congested  con- 
dition. 

After  the  hot  bath,  a  short  cold  shower  or  a  quick 
cold  rub  should  be  taken ;  or  a  pailful  of  cool  water 
may  be  poured  over  the  body.  This  will  stimulate 
the  nerves  of  the  skin  and  prevent  the  taking  of  cold 
afterwards.  It  will  also  stir  up  the  white  blood  cells 
to  greater  activity  and  so  assist  in  the  work  of  getting 
well  again. 

Another  way  in  which  human  beings  living  in  cold 
countries  have  learned  to  lessen  the    escape  of  heat 
from  the  body  is  by  clothing.     The  natural  gavin 
clothing  of  the  body  is  the   skin   and  hair,  heat  loss 
This  is  true  of  man  as  well  as  of  other  ani-  b? 
mals.     Savage   tribes  who   live   in   the   mild 
climate  to  which  man  is  naturally  adapted  find  little 
or  no  clothing  necessary  for  either  comfort  or  health. 

But  experiments  have  shown  that  it  is  not  possible, 
for  the  body  to  maintain  its  temperature  if  exposed 
without  clothing  to  air  at  a  temperature  of  less  than 
86  degrees  F.  The  temperature  in  which  an  individual 
actually  lives  is  that  of  the  air  next  to  the  body,  inside 
of  the  clothing.  Clothes  lessen  the  loss  of  heat  from 
the  body  by  keeping  it  in  a  jacket  of  still  air,  which  is 
an  exceedingly  bad  conductor  of  heat.  Each  additional 
garment  makes  another  "air  jacket."  For  this  rea- 
son, several  thin  garments  are  much  warmer  than 
one  thick  one,  just  as  a  house  with  double  walls  and 
windows,  inclosing  a  layer  of  air,  is  warmer  than  one 


166  THE   BODY  IN   HEALTH 

with  single  walls  and  windows,  though  they  may  be  of 
double  thickness.  When  one  throws  off  a  garment 
he  at  the  same  time  removes  one  of  his  "air  jackets." 

Sufficient  clothing  should  be  worn  to  maintain  the 
temperature  of  the  air  in  contact  with  the  body  at 
from  77  to  86  degrees  F.  This  requires  for  the  ordinary 
man  about  six  to  eight  pounds  of  clothing  in  the  sum- 
mer, and  twice  as  much  in  the  winter  season  if  he  is 
exposed  to  the  outdoor  temperature.  Those  who  live 
indoors  in  heated  rooms  require  very  little  more  cloth- 
ing in  winter  than  in  summer,  while  they  remain 
indoors. 

Animals  regulate  their  skin  clothing  to  suit  the 
season,  growing  a  thick  cover  for  protection  in  the 
winter  season  and  shedding  their  thick  "hair  in  the 
spring. 

A  matter  of  the  highest  importance  is  the  arrange- 
ment of  clothing  on  the  body  so  that  there  shall  not 
be  too  much  heat  in  certain  parts,  while  other  parts 
are  not  sufficiently  protected.  The  arms  and  legs, 
and  particularly  the  feet,  require  special  protection,  for 
the  reason  that  they  are  farthest  from  the  heat  centers, 
while  they  present  a  larger  surface  for  heat  loss  in  pro- 
portion to  their  weight  and  the  amount  of  blood  sup- 
plied to  them  than  does  the  trunk.  Many  persons 
suffer  greatly  and  are  often  made  sick  from  insufficient 
clothing  of  the  limbs  in  the  cold  seasons,  without 
being  aware  of  the  cause  of  their  illness.  When  the 
arms  and  the  limbs  are  chilled,  their  blood  vessels  will 


REGULATING   BODY  TEMPERATURE       167 

be  contracted,  and  consequently  some  internal  part 
will  get  more  than  its  share  of  blood.  Congestion  of 
the  head  and  various  troubles  with  the  internal  organs 
may  result  from  this  source. 

The  material  of  which  clothing  is  made  has  a  very 
important  relation  to  health,  because  different  fabrics 
behave  very  differently  in  regard  to  letting  heat  escape 
from  the  body,  taking  up  moisture  and  permitting  air 
to  circulate  about  the  body.  Linen  absorbs  moisture 
much  more  rapidly  than  does  wool  and  dries  more 
than  twice  as  quickly.  This  is  also  true  of  cotton  to  a 
less  degree  and  to  a  still  less  degree  of  silk. 

Cotton  has  a  flat  and  twisted  fiber  that  can  be  manufac- 
tured into  a  much  more  elastic  cloth  than  can  linen,  the 
fibers  of  which  are  cylindrical,  straight,  and  stiff.  Wool 
fiber  has  a  jagged,  scale- 
like  surface,  and  is  soft 
and  so  elastic  that  it  is 
difficult  to  produce  from 
it  a  compact  thread,  and 
when  woven  the  cloth 
furnishes  a  great  num- 
ber of  air  spaces  between 
the  meshes.  Clothing 
made  from  wool  is  both 
very  warm  and  very 

light.       Wool    garments,         COTTON  HAS  A  FLAT  AND  TWISTED  FIBER. 

however,  are  very  likely  to  shrink  and  "full"  when 
washed,  unless  very  carefully  laundered.  In  that 


i68 


THE   BODY  IN  HEALTH 


case,  the  air  spaces  between  the  meshes  and  the 
elasticity  of  the  fabric  are  diminished,  until  it 
sometimes  happens  that  undergarments  and  hose  of 
all  wool  after  frequent  washings  become  almost  air 

tight,  which  is  very  bad 
for  the  body,  as  you 
know. 

As  the  skin  is  con- 
stantly throwing  off 
moisture,  it  is  very  im- 
portant that  the  cloth- 
ing should  be  able  to 
take  it  up  and  pass  it 
out  to  the  air.  Woolen 
goods  hold  the  moisture 
for  a  long  time.  Wool 
is  on  this  account  not 
well  adapted  for  garments  to  be  worn  next  to  the 
skin.  Cotton  is  superior  to  all  other  fabrics  for  this 
purpose.  Linen  stands  next  in  value.  The  fact 
that  the  quick  drying  of  linen  or  cotton  exposes  the 
skin  to  rapid  cooling  by  evaporation  necessitates 
the  wearing  of  outer  garments  of  wool  to  prevent  the 
too  rapid  loss  of  heat  during  those  seasons  of  the 
year  when  extra  precaution  is  required. 

The  wearing  of  cotton  next  to  the  body  is  conducive 
to  cleanliness.  Cotton  undergarments  prevent  undue 
heating  of  the  skin  and  accumulation  of  moisture, 
the  latter  of  which  has  the  effect  to  relax  the  skin  and 


WOOL     HAS    A    JAGGED,     SCALE-LIKE     SUR- 
FACE. 


REGULATING  BODY  TEMPERATURE       169 

keep  in  a  moist  and  decomposing  state  the  waste 
matters  thrown  off  by  it.  Cotton  may  be  worn  at  all 
seasons  of  the  year.  It  is  only  necessary  to  provide 
sufficient  outer  clothing  to  secure  the  necessary  warmth. 
An  additional  thick  union  suit  will  afford  better  pro- 
tection than  extra  outer  wraps. 


HEALTH  PROBLEMS 

1.  See  if  you  can  get  a  physician's  thermometer  and  find  out 
your  internal  temperature.     The  physician  will  tell  you  to  put  the 
thermometer  under  your  tongue.     Why  would  it  not  do  to  put  it 
on  the  surface  of  your  body  ? 

2.  Take  your  temperature  if  you  can  on  a  hot  day  and  on  a 
cooler  day  to  see  whether  the  temperature  varies  according  to  the 
weather. 

3.  Get  the  temperature  of  a  frog  or  a  snake  if  you  can  on  a 
warm  day  and  on  a  cooler  day.     Does  the  temperature   change 
with  the  weather  ?     Explain. 

4.  Mention  a  number  of  warm-blooded  animals.     Mention  a 
number  of  cold-blooded  animals. 

5.  Suppose  you  were  out  in  the  open  air  and  the  temperature  of 
the  air  should  drop  thirty  or  forty  degrees.     What  would  happen 
if  you  had  no  extra  clothing  to  put  on  ?     Explain. 

6.  Suppose  one  could  not  shiver  when  he  was  chilly.     Would 
this  be  any  disadvantage  to  his  body  ? 

7.  Why  is  there  so  little  blood  at  the  surface  of  the  body  when 
one  first  goes  out  on  a  cold,  biting  day  ?     Why  is  there  so  much 
heat  at  the  surface  of  the  body  when  it  is  a  hot  day  ? 

8.  Explain  why  it  is  that  people  who  live  in  cold  countries  are 
often  large  and  "ruddy,"  while  people  who  live  in  warmer  coun- 
tries are  often  thin  and  pale. 


i;o  THE  BODY  IN  HEALTH 

9.  Tell  the  class  some  way  to  show  that  evaporation  takes  heat. 
Think  of  some  way  not  mentioned  in  your  lesson. 

10.  Show  in  some  simple  way  that  evaporation  from  the  skin 
cools  it. 

11.  Think  of  some  way  in  which  you  could  make  it  plain  to  a 
person  what  it  meant  to  raise  half  a   ton  of  water   one   degree 
of  temperature.      Figure  out  what  you  could  do  with   the  heat 
required  for  this,  if  you  could  collect  it  all  and  use  it  just  as  you 
wanted  to. 

12.  Is  it  a  good  thing  to  have  very  dry  air  in  winter  when  one 
wants  to  keep  warm  ?     Is  it  a  good  thing  to  have  moist  air  in 
summer  when  one  wants  to  keep  cool  ? 

13.  Why  does  one  feel  colder  where  there  is  a  wind  than  he  does 
where  it  is  quiet,  even  though  the  thermometer  may  be  the  same 
in  both  places  ? 

14.  Why  are  the  people  in  northern  countries  usually  more 
active  than  those  in  the  tropics  ? 

15.  Have  you  noticed  that  you  are  often  cooler  on  a  hot  day 
when  you  play  or  work  than  when  you  lie  around  in  the  house  ? 
Explain. 

1 6.  Have  you  ever  noticed  that  when  you  have  been  in  a  room 
in  winter  up  to  80  degrees,  you  will  feel  chilly  when  you  go  out 
into  cold  air  ?     Explain. 

17.  See  if  you  can  find  out  what  is  usually  the  cause  of  your 
colds.     How  do  you  treat  your  colds  ?     Do  you  take  patent  med- 
icine, cough  drops,  and  the  like  ? 

1 8.  Show  why  storm  windows  help  to  keep  a  house  warm,  even 
when  there  is  no  wind. 

19.  Suppose  you  could  have  an  undergarment  woven  so  that 
you  could  not  possibly  see  through  it,  and   could   have  another 
which  was  porous,  and  they  were  both  the  same  weight,  which 
would  you  choose  ?     Why  ? 

20.  Try  soaking  a  piece  of  wool,  a  piece  of  cotton,  and  a  piece 
of  silk  in  water  until  they  are  thoroughly  wet.     Then  take  them 


REGULATING  BODY  TEMPERATURE       171 

out    and    see   which    one    will    become    dry   the   more    rapidly. 
Explain. 

REVIEW  QUESTIONS 

1.  What  would  happen  to  the  body  if  the  internal  temperature 
should  change  very  much  ? 

2.  How  is  the  warmth  of  the  body  kept  up  ? 

3.  Where  are  the  heat-making  processes  in  the  body  carried  on 
chiefly  ?     How  is  the  amount  of  heat  made  in  the  body  regulated  ? 

4.  How    does  the    body  protect    itself  from    undue  heat  or 
cold  ? 

5.  Tell  particularly  about  the  work  of  the   sweat   glands   in 
regulating  the  loss  of  heat. 

6.  Tell  about  the  experiment  made  by  the  men  who  stayed  in  a 
room  heated  to  260  degrees  F. 

7.  What  sort  of  air  must  one  have  in  order  that  the  sweat  may 
evaporate  freely  ?     Why  does  one  usually  feel  uncomfortable  on 
a  muggy  day  ? 

8.  Why  is  it  that  in  a  fever  the  temperature  of  the  body  be- 
comes higher? 

9.  What  is  a  good  way  to  reduce  the  temperature  of  the  body 
when  there  is  a  fever  ? 

10.  What  is  the  influence  of  exercise  upon  the  making  of  heat  in 
the  body  ? 

11.  Why  does  one  usually  feel  inactive  on  a  very  hot  day  ? 

12.  How  does  the  kind  of  food  one  eats  affect  the  heat-making 
in  his  body  ? 

13.  Why  is  one  likely  to  take  cold  when  he  lives  in  houses  that 
are  very  hot  ? 

14.  What  is  likely  to  happen  to  one  when  he  stays  in  a  room 
that  is  very  cold  ? 

15.  What  happens  to  the  internal  organs  when  one  has  a  cold  ? 

16.  Why  should  one  always  follow  a  hot  bath  with  a  cold  spray 
or  a  dash  of  cold  water  ? 


172  THE   BODY   IN   HEALTH 

17.  How  does  clothing  help  to  prevent  too  great  loss  of  heat  in 
the  body?     Just  how  is  clothing  able  to  keep  the  body  warm? 

1 8.  Why  is  it  better  to  wear  several  light  garments  in  winter 
than  one  very  thick  and  heavy  one  ?     What  sort  of  clothing  is  best 
to  be  worn  next  to  the  skin  ? 

19.  What  parts  of  the  body  should  be  clothed  particularly  well 
in  winter  and  why  ? 

20.  What  kind  of  clothing  should  be  avoided  ?    Why  ? 


CHAPTER  X 
THE  FRAMEWORK  OF  THE  BODY 

SOME  of  the  work  of  the  body  —  that  of  supporting 
itself --is  too  heavy  for  the  soft  cells  to  do  alone. 
They  therefore  build  up  around  themselves  The  nature 
solid  structures,  in  much  the  same  way  as  a  and  uses  of 
snail  builds  its  house,  and  a  turtle  its  shell,  the  bones" 
out  of  its  own  body.  Bone  and  cartilage,  which  make 
the  solid  framework  of  the  body,  are  formed  in  this 
way. 

The  skeleton  of  a  new-born  baby  is  composed  wholly 
of  cartilage,  which,  as  you  know,  is  not  so  hard  as  bone. 
It  is  so  pliable  that  the  bones  of  a  little  child  may  be 
easily  bent. 

The  bones  are  gradually  hardened  as  they  grow  by 
the  bone  cells  building  lime  into  them.  By  the  time 
they  are  full  grown  only  a  thin  layer  of  cartilage  on 
the  ends  of  the  bones  remains.  In  order  that  they 
may  be  properly  developed,  the  food,  especially  of 
young  children,  should  contain  a  sufficient  quantity 
of  lime.  Milk  and  whole-wheat  bread  are  good  bone- 
building  foods.  Why  ? 

If  the  lime  or  mineral  matter  is  dissolved  out  of  a 
fresh  bone  by  acid  the  animal  part  that  remains  will 

173 


174 


THE   BODY  IN  HEALTH 


cav/ty 


be  found  so  flexible  that  if  the  bone  is  long  and  slender, 
it  may  be  easily  tied  in  a  knot.  The  more  lime  there 
is  in  the  bones,  the  less  pliable  and  the  more  brittle 
they  become.  The  proportion  of  lime 
in  the  bones  seems  to  increase  from 
year  to  year  through  life.  For  this 
reason  the  bones  of  aged  persons  are 
very  easily  broken. 

Bones  are  covered  by  a  tough  mem- 
brane called  the  periosteum,  which 
contains  a  few  nerves  and  numerous 
blood  vessels  through  which  the  bone 
is  nourished  and  developed. 

If  the   large   bones   of  the  human 
body  were  solid,  they  would  be  very 
much    heavier    without    being    much 
stronger.      Of   course,   you    see    it    is 
necessary  they  should  be  not  only  firm 
and    strong  but    light    enough    to    be 
easily  moved.     If  you  look  at  the  pic- 
ture of  a  •  cut  through  a  long   bone, 
you  will  see  that  it  is  only  the  outer 
layer  that  is  composed  of  solid  bone. 
LONGITUDINAL  SEC-     Of  what  is  the  inner  layer  composed  ? 
TION  OF  THE     YOU  should  note  especially  that  in  the 
middle  there  is  a  canal  or  hollow  space. 
Do  you  see  that  cavities  in  the  bones  not  only  give 
lightness,  but  they  also  increase  the  strength  of  the 
bones  ?     Can  you  explain  why  ? 


THE  FRAMEWORK  OF  THE   BODY         175 

J 

Skulh 


Trunk 


Arm 


THE   FRAMEWORK  OF  THE    BODY. 


176  THE   BODY  IN  HEALTH 

An  experiment  with  a  sheet  of  paper  and  a  book 
will  show  that  when  the  paper  is  rolled  into  a  hollow 
cylinder,  it  will  support  more  weight  than  in  any  other 
form.  Mention  other  instances  in  which  nature  makes 
use  of  this  device  to  secure  a  combination  of  lightness 
and  strength.  Think  of  some  ways  in  which  man 
makes  use  of  this  same  fact. 

It  is  in  the  bones  that  the  red  corpuscles  of  the  blood 
are  formed.  The  cavities  of  the  long  bones  are  filled 
with  a  substance  called  marrow,  containing  nerve  and 
blood  vessels  and  large  quantities  of  fat,  which  gives 
it  a  yellow  color.  In  the  smaller  cavities  of  the  spongy 
bone  the  marrow  contains  less  fat  and  is  of  a  red  color, 
because  it  is  here  that  the  red  corpuscles  are  being 
formed. 

Without  a  skeleton,  the  body  would  not  be  able  to 
hold  itself  upright.  One  of  the  chief  uses  of  the  bones 
is,  therefore,  to  support  the  body. 

It  is  easy  to  see,  is  it  not,  that  without  the  bones  the 
various  movements  of  the  different  parts  of  the  body, 
as  in  walking,  raising  the  arms,  would  not  be  possible  ? 
The  bones  aid  in  moving  the  body  and  its  various  parts. 
Each  bone  has  roughened  places  and  ridges  to  which 
muscles  are  attached,  and  the  bones  thus  provide 
levers  by  means  of  which  the  muscles  are  able  to  move 
the  body. 

Another  important  use  of  the  bones  is  to  protect 
from  injury  the  delicate  and  sensitive  parts  of  the 
body.  You  can  feel  the  strong  box  that  the  bones  of 


THE   FRAMEWORK  OF  THE   BODY         177 

your  head  form  for  the  protection  of  your  brain.  The 
spinal  cord  into  which  the  brain  passes  is  guarded  by 
the  bony  tube  called  the  spinal  column.  You  can 
feel  also  the  strong  framework  of  bone 
that  protects  the  lungs  and  the  heart. 

The  body  of  a  new-born  baby  has  as 
many  bones  as  that  of  a  full-grown  man  — 
206.  They  are  of  different  sizes  and  shapes, 
according  to  the  use  that  is  to  be  made 
of  them.  Some  are  long,  as  those  in  the 
legs  and  arms  ;  some  short,  as  in  the  wrist ; 
some  flat,  as  in  the  upper  part  of  the'skull ; 
some  curved,  as  in  the  ribs.  You  can  feel 
most  of  your  own  bones  and  decide  for 
yourself  why  each  has  its  own  particular 
shape.  By  studying  the  picture  of  the 
skeleton  and  comparing  it  with  your  own 
body,  you  can  easily  locate  all  the  principal 
bones  and  find  out,  if  you  wish,  the  names 
that  have  been  given  to  them. 

The  most  important  and  interesting  of 
the  bony  structures  of  the  body  is  the  spinal  column. 
It  is  necessary  that  it  should  be  strong  enough  to  sup- 
port the  trunk  and  the  head  and  protect  the  spinal  cord. 
At  the  same  time,  it  must  be  flexible  enough  to  bend 
with  ease  in  any  direction  with  the  movements  of  the 
trunk,  yet  in  such  a  manner  that  the  delicate  spinal 
cord  within  it  shall  not  be  injured.  This  wonderful 
combination  of  uses  is  accomplished  by  the  arrangement 


THE   SPINAL 

COLUMN 


i78  THE   BODY  IN  HEALTH 

of  a  number  of  separate  ring-like  bones,  one  above 
another,  bound  together  with  bands  of  strong  connec- 
tive tissue  known  as  ligaments.  These  bones  are  called 
the  vertebrae.  The  bony  column  with  a  canal  running 
through  it,  which  is  formed  by  the  twenty-four  vertebrae 
when  they  are  arranged  one  above  the  other,  is  shown 
in  the  illustration. 

The  vertebrae  are  separated  from  each  other  by  means 
of  disks  composed  of  very  elastic  cartilage.  These  act 
Buff  as  t>uffers  to  prevent  friction  and  jarring 

prevent  which  might  injure  the  brain.  A  person 
jarring  in  wno  is'much  on  his  feet  becomes  shorter 
during  the  day  by  the  thinning  of  the  carti- 
lages between  the  vertebrae  ;  but  he  regains  his  height 
during  the  night.  Most  persons  are  half  an  inch 
taller  in  the  morning  than  at  night. 

You  will  notice  in  the  picture  that  the  spinal  column 
is  not  straight  but  forms  a  graceful  double  curve.  It 
is  upon  the  preservation  of  the  natural  curves  of  the 
spine  that  the  poise  and  graceful  carriage  of  the  body 
chiefly  depend.  These  curves  also  aid  in  giving  spring- 
iness to  the  spinal  column  and  so  preventing  jarring 
of  the  head  in  walking  or  running. 

Notice  the  difference  in  the  amount  of  jar  the  body 
receives  in  jumping  with  the  legs  straight  and  stiff 
and  with  the  legs  bent  at  the  knees  ;  also  the  difference 
in  the  jarring  of  the  hand  when  the  ground  is  struck 
with  a  straight  stick  and  with  a  curved  one.  The 
curves  in  the  spine,  the  arch  of  the  foot,  and  the  bend- 


THE   FRAMEWORK  OF  THE   BODY         179 

ing  of  the  knee,  as  well  as  the  cartilages  separating 
the  vertebrae,  all  aid  in  protecting  the  brain  by  giving 
greater  springiness  to  the  skeleton  and  so  preventing 
jarring. 

If  the  spinal  column  is  broken  it  is  quite  impossible 
to  stand  or  walk,  since  there  is  no  support  for  the 
trunk,  and  the  spinal  cord  which  controls  the  move- 
ments of  the  muscles  is  injured.  It  is,  however,  so 
flexible  that  such  an  accident  rarely  happens. 

If  the  bony  framework  of  the  body  were  all  united 
in  one  piece,  no  movement  of  the  different  parts  of  the 
body  would   be   possible.     If,   on  the  other  The 
hand,    it    were    composed    of    disconnected  J*oints- 
bones,  there  would  be  no  support  for  the  body  as  a 
whole  and  it  would  not  be  able  to  stand  upright.     It 
is  necessary  that  the  bones  should  be  joined  together, 
but  in  such  a  way  that  the  free  movements  of  the  parts 
should  be  possible.     The  places  where  the  bones  are 
united  are  called  joints. 

Where  great  strength  but  no  movement  is  required, 
the  bones  are  solidly  united  by  immovable  joints. 
Since  there  is  no  movement  at  these  joints,  we  cannot 
detect  them  in  our  own  bodies,  but  they  may  easily  be 
seen  in  the  skeleton  of  the  head  for  instance.  Most  of 
the  bones  are  united  by  movable  joints.  Why,  do  you 
think  ? 

In  an  immovable  joint,  the  bones  are  firmly  united 
by  a  piece  of  cartilage  that  grows  between  them.  In  a 
movable  joint,  a  thin  layer  of  cartilage  covers  the 


i8o 


THE   BODY  IN  HEALTH 


end  of  each  bone,  and  this  is  kept  lubricated,  or  moist, 
by  an  oily  fluid  poured  out  by  a  delicate  membrane 
that  incloses  the  joint.  This  enables  the  joints  to 
work  very  smoothly  and  noiselessly. 

The  joints  are  bound  together  by  tough  bands  of 
connective  tissue  called  ligaments.  Besides  holding 

the  bones  together,  these 
ligaments  also  limit  the 
movements  of  the  joints. 
There  are  several 
kinds  of  movable  joints. 
In  the  ball-and-socket 
joint,  the  rounded  end 
of  one  bone  fits  into  a 
cuplike  hollow  in  another 
bone.  This  kind  of  joint 
is  found  in  the  shoulder 
and  the  hips.  It  gives 
the  greatest  freedom  of 
motion,  allowing  move- 
ment in  all  directions,  as  you  may  see  by  swinging 
your  arms  or  legs.  Hinge  joints,  examples  of  which 
are  found  in  the  elbow  and  the  finger,  allow  move- 
ment only  in  two  opposite  directions.  In  gliding 
joints,  the  bones  move  slightly  upon  each  other,  as 
at  the  wrist  and  ankle. 

The  vertebrae  have  a  special  kind  of  joint.  They 
rock  back  and  forth  on  each  other,  as  they  are  pulled 
by  the  muscles  that  control  them,  the  amount  of 


BALL-AND-SOCKET  JOINT. 


THE  FRAMEWORK  OF  THE  BODY    181 

movement  being  limited  by  the  ligaments  that  hold 
them  together. 

In  consequence  of  a  fall  or  a  blow,  the  end  of  a  bone 
is  sometimes  dislocated  or  "put  out  of  joint."     The 
ligaments   about   the  joint   are  broken,   and  injuries  of 
the  bone  slips  out  of  place.     On  the  occur-  the  bones 
rence  of  such  an  accident,  a  physician  should  and  Joints- 
be  called  at  once,  before  the  parts  become  swollen. 
Why  will  they  swell  ? 

A  sprain  is  an  injury  due  to  a 
strain  of  a  joint  resulting  in  a  liga- 
ment's being  torn  from  its  fasten- 
ings to  the  bone.  Bathing  in  water 
as  hot  as  can  be  borne  will  keep 
down  the  swelling  and  relieve  the 
pain.  Why  ?  Elevation  of  the  in- 
jured member  will  also  help  to  keep 
down  the  inflammation.  Why  ? 

When  a  bone  is  broken,  the  mus- 
cles often  draw  the  ends  of  the 
broken  bone  apart  and  a  physician  is  required  to  put 
them  in  proper  position.  There  may  be  sharp  points 
on  the  ends  of  the  broken  bones,  which  are  likely  to 
tear  the  tissues  if  the  limb  is  bent  at  the  broken 
point.  On  this  account,  great  care  should  be  taken 
to  keep  the  limb  perfectly  straight  until  the  phy- 
sician arrives.  After  being  "set,"  the  ends  of  the 
bone  must  be  held  in  position  by  splints  and  bandages 
until  Nature  has  time  to  cement  the  parts  together 


182  THE   BODY  IN  HEALTH 

by  means  of  a  jellylike  substance  produced  between 
and  around  the  ends  of  the  broken  bone.  This  sub- 
stance gradually  hardens  and  becomes  as  firm  as  bone? 
making  the  bone  nearly  as  good  as  before. 

The  effects  of  tobacco  poison  in  preventing  the 
proper  development  of  the  bones  is  so  marked  that 
even  those  who  allow  its  use  by  adults  condemn  its 
use  by  growing  boys.  We  have  already  seen  that  the 
heart,  the  lungs,  and  the  digestive  organs  are  injured 
by  tobacco,  so  that  no  part  of  the  body  gets  its  proper 
supply  of  food  and  oxygen.  The  bones  suffer  as  well 
as  the  rest  of  the  body  from  this  lack.  Besides  this, 
the  tobacco  poison  seems  to  have  a  special  effect  in 
injuring  the  bone  cells  and  checking  the  development 
of  the  bones.  A  boy  who  early  begins  to  smoke  ciga- 
rettes is  almost  sure  to  be  dwarfed  and  stunted  in  body 
as  well  as  in  mind. 

If  you  should  fasten  the  bones  of  a  skeleton  to- 
gether with  artificial  joints  and  then  try  to  make  it 
Keeping  stand  upright,  you  would  find  you  could  not 
straight.  Jo  so .  ;t  would  all  fall  together  in  a  heap  of 
bones.  There  must  be  something  besides  the  joints 
to  hold  the  bones  together  and  keep  them  in  their 
proper  position.  This  work  is  done  by  the  muscles. 
The  skeleton  could  no  more  stand  alone  without  the 
aid  of  the  muscles  than  the  muscles  could  stand  with- 
out the  skeleton. 

It  is  of  great  importance  that  every  group  of  muscles 
in  the  body  should  be  properly  developed  so  that  the 


THE  FRAMEWORK  OF  THE  BODY         183 


NAMES  OF  MUSCLES 

a  -  Occipito  Front 3 I  is 

b-  Temporal 

c-Massefer 

d-  Sterno-Cleido-Mastoid 

e-  Deltoid 

f  -  Pectorslis  Major 

g-  Pectoralis  Minor 

h  -  Obliquus  Extern u s 

\  -  RectusAbdominalis 

j-  Biceps 

k-  Triceps 

\-Glutedl  Musc/e 


n-Sarfor/vs 

o- -Abductor  Muscles 


remons 

q-  Vast os  Externus 
r-  T/bialisAnticus 
S-  Extensors  of  the  Toes 

NOTICE  AT  WHAT  POINTS  SOME  OF  THE  MORE  IMPORTANT  MUSCLES  ARE  ATTACHED. 

EXPLAIN. 


1 84 


THE   BODY  IN   HEALTH 


skeleton  may  be  held  erect.  It  should  be  supported 
equally  on  every  side,  like  the  masts  and  spars  of  a 
full-rigged  vessel.  This  is  necessary  in  the  first  place 
in  order  to  have  a  good  appearance. 

We  bear  in  our  bodies  a  sort  of  record  of  our  habits 


WHAT  SORT  OF  A  HABIT  is  THIS  BOY 
FORMING  ? 


AND  THIS  ONE  ? 


that  may  be  easily  read  by  a  trained  eye.  A  slouch- 
ing body  and  a  shuffling  walk  create  a  most  unfavorable 
impression  of  carelessness,  laziness,  and  lack  of  dignity 
and  self-respect.  A  boy  who  walks  with  head  erect 
and  shoulders  well  squared  gives  an  impression  of 
energy  and  self-respect  which  is  of  great  advantage 


THE   FRAMEWORK  OF  THE   BODY         185 


to  him.  A  girl  with  a  fine 
carriage  and  graceful  walk 
makes  a  much  finer  appear- 
ance than  one  who  neglects 
to  hold  herself  erect  and  who 
walks  with  a  careless  gait. 

We  are  in  some  respects 
the  architects  of  our  own 
bodies.  It  is  more  or  less 
in  our  power  to  determine 
the  shape  of  the  body.  Es- 
pecially in  youth  when  the 
bones  are  pliable  and  the 
muscles  supple,  we  may,  ac- 
cording to  our  habits,  in- 
fluence the  position  of  the 
bones  and  their  relations  to 
each  other.  We  may  then 
determine  whether  we  shall 
have  a  well-shaped  body  and 
erect  carriage  that  will  at 
once  recommend  us  to  others 
or  an  awkward  carriage  and 
ungainly  body  that  will  al- 
ways be  a  handicap  to  us. 

The  symmetrical  develop- 
ment of  the  body  is  of  even 
more   importance  for  the   sake  of   health    than    for 
that  of  a  good  appearance.     An  external  deformity 


Do  YOU   APPROVE    OF    THIS    BOY*S 
WALKING   HABIT  ? 


186  THE   BODY  IN   HEALTH 

usually  means  a  corresponding  internal  deformity; 
the  latter  is  of  far  greater  importance  than  the  former. 
Round  shoulders,  for  instance,  are  always  accompanied 
by  a  flat  chest.  This  means  the  lungs  will  be  com- 
pressed and  therefore  the  breathing  capacity  will  be 
lessened. 

It  is  only  by  exercise  that  the  suppleness  of  the 
body,  the  elasticity  of  the  muscles,  and  the  flexibility 
HOW  de-  °f tne  tendons  and  ligaments  can  be  preserved, 
formities  If  the  muscles  of  a  certain  part  of  the  body  are 
are  caused.  nQt  use(j  jn  sucn  a  manner  as  to  stretch  them, 

they  may  become  shortened  and,  after  this,  stretching 
them  will  be  impossible.  If  the  arm  be  kept  bent  for 
a  long  time,  it  may  become  impossible  to  straighten 
it,  because  the  muscles  of  the  inner  surface  of  the  arm 
will  have  become  shortened  through  not  being  stretched. 
This  illustrates  how  deformities  may  be  produced 
through  the  pulling  out  of  place  of  the  bones,  which 
may  be  permanently  held  there  by  a  shortening  of  the 
muscles. 

The  vertebrae  of  the  spinal  column  are  moved  by 
the  contracting  and  lengthening  of  the  muscles  attached 
to  them.  When  the  spine  is  curved  on  the  left  side, 
the  muscles  on  the  right  side  contract  and  are  shortened, 
and  a  curvature  of  the  right  side  means  a  shortening 
of  the  muscles  on  the  left  side.  When  the  body,  in 
sitting,  standing,  or  working,  is  habitually  held  in  an 
improper  position,  some  of  the  muscles  may  become 
permanently  shortened,  causing  a  life-long  deformity, 


THE   FRAMEWORK  OF  THE   BODY         187 


known  as  spinal  curvature.  A  backward  curvature  of 
the  spine,  manifested  by  round  shoulders,  a  flat  or 
hollow  chest,  for- 
ward carriage  of 
the  head,  and  an 
unnatural  straight- 
ness  of  the  back,  is 
by  far  the  most  com- 
mon form  of  spinal 
curvature.  If  the 
muscles  of  the  back 
are  relaxed,  the  spine 
naturally  falls  back- 
ward by  its  own 
weight.  This  is 
what  makes  the 
chest  flat.  The 
trouble  is  not  in  the 
chest,  but  in  the 
spine,  and  the  curvature  of  the  spine  is  due  to  the 
relaxation  of  the  muscles  of  the  back  allowing  the 
spine  to  bend  backward. 

HEALTH  PROBLEMS 

1.  Suppose  a  boy  five   years   old  and  one  twenty  years  old 
should  fall  from  a  limb  of  a  tree,  say  a  distance  of  twenty-five  feet. 
Do  you  think  it  probable  that  either  boy  would  break  the  bones  in 
his  leg  or  in  some  other  part  of  his  body?     Which  do  you  think 
would  be  most  likely  to  escape  injury  ?     Explain. 

2.  Suppose  you  put  a  man  of  fifty  in  place  of  the  boy  of  five, 


WHAT  MAY  HAPPEN  TO  ONE  WHO  GETS   IN  THE 
HABIT  OF  SITTING    BENT  OVER  A  TABLE  OR 

A   DESK  ? 


188  THE   BODY  IN  HEALTH 

which  one  of  the  persons  falling  would  then  be  most  likely  to 
suffer  ? 

3.  Suppose  that  the  boy  of  five,  the  young  man  of  twenty,  and 
the  man  of  fifty  years  should  each  break  the  bones  in  his  leg. 
Which    one  of   the  three    persons  do  you  think  would  recover 
soonest  ? 

4.  If  you  had  to  break  a  bone  in  your  arm  or  your  leg,  at  what 
age  should  you  choose  to  have  it  occur,  if  you  could  have  your 
choice  ?     Explain. 

5.  It  was  said  in  this  chapter  that  the  bones  of  a  child  are  soft. 
Do  you  think  Nature  planned  this  for  a  particular  purpose  ?     If  so, 
mention  it. 

6.  Try  the  experiment  of  taking  the  lime  out  of  a  bone  and 
notice  what  happens  to  it. 

7.  Try  the  experiment  of  burning  the  animal  part  out  of  a  bone 
and  notice  what  happens  to  it. 

8.  Can  you  give  a  reason  why  the  red  corpuscles  should  be 
made  in  the  marrow  of  bones  ? 

9.  Suppose  you  had  a  non-flexible  spinal  cord.     What  should 
you  be  prevented  from  doing  that  you  can  now  do  ? 

10.  Try  the  experiment  of  trying  to  hold  your  body  perfectly 
stiff  and  then  jump  up  and  down  on  your  heels,  though  not  very 
high,  of  course.     How  do  you  feel  ?     What  reason  can  you  give 
for  this  experience  ? 

n.  In  your  own  body  point  to  some  immovable  joints.  Why 
did  nature  not  make  them  movable  ?  Why  did  she  not  make 
them  in  one  piece  so  that  there  would  be  no  joints? 

12.  A  boy  I  know  had  his  leg  broken  in  a  football  game.     He 
did  not  have  the  surgeon  come  at  once.     It  is  now  six  months 
since  the  accident  occurred,  and  the  break  has  not  yet  healed, 
though  he  is  a  healthy  boy.     What  do  you  think  might  be  the 
explanation  of  this  ? 

13.  Mention  some  deformities  in  people  which  could  have  been 
avoided  by  good  habits  of  sitting,  standing,  and  walking. 


THE   FRAMEWORK  OF  THE   BODY         189 

'•[   • 

I 

REVIEW  QUESTIONS 

1.  How  does  the  body  secure  a  framework  to  support  itself? 

2.  What  makes  up  the  framework  of  the  body  ? 

3.  Of  what  is  the  skeleton  of  a  new-born  baby  composed  ? 

4.  What  is  the  cause  of  such  a  deformity  as  knock-knee  and 
bowleg  ? 

5.  What  makes  the  bones  hard  ?     Give  a  description  of  each 
part  of  which  the  bone  is  composed. 

6.  What  kind  of  food  do  young  children  need  in  order  to  build 
their  bones  ? 

7.  What  is  the  periosteum  ? 

8.  Why  did  nature  not  make  the  large  bones  of  the  body  solid  ? 

9.  How  does  nature  secure  lightness  and  strength  in  bones  ? 

10.  What  are  the  uses  of  the  skeleton  ? 

11.  What  is  the  arrangement  so  that  the  muscles  can  move  the 
bones  ? 

12.  How  many  bones  are  there  in  the  human  body?    What 
are  their  shapes  ? 

13.  What  is  the  spinal  column  ? 

14.  How  is  the  spinal  column  made  so  that  it  is  very  flexible  ? 

15.  What  are  the  bones  in  the  spinal  column  called  ? 

16.  What  is  the  use  of  the  disks  that  separate  the  vertebrae  ? 

17.  Why  is  a  person  taller  in  the  morning  than  he  is  at  night  ? 

1 8.  Of  what  value  is  it  to  have  the  double  curve  in  the  spine  ? 

19.  What  are  the  ways  in  which  Nature  tries  to  prevent  too 
great  jarring  of  the  brain  when  one  walks,  runs,  or  jumps  ? 

20.  If  the  spinal  column  should  be  broken,  what  would  happen 
to  the  body  ? 

21.  What  is  the  purpose  of  the  joints  that  join  the  bones  to- 
gether ?     What  is  meant  by  immovable  joints  ?     Mention  some 
of  these  joints.     What  is  meant   by  movable  joints  ?     Mention 
some  of  these. 

22.  What  is  the  use  of  the  ligaments  in  the  body  ? 


190  THE   BODY  IN  HEALTH 

23.  Give  an  example  of  the  ball  and  socket  joint;  of  the  hinge 
joint ;   of  the  sliding  joint. 

24.  What  does  it  mean  to  have  a  bone  dislocated  ? 

25.  What  is  a  sprain  ?     How  should  you  treat  a  sprain  ? 

26.  What  should  be  done  in  case  a  bone  is  broken  ? 

27.  What  is  the  effect  of  tobacco  on  the  bones  ? 

28.  What  is  needed  besides  bones  and  joints  to  keep  the  body 
upright  ? 

29.  Can  we  do  something  toward  securing  good  appearance  ?    If 
so,  what  can  we  do  ? 

30.  What  does  a  slouching  body  and  a  shuffling  walk  indicate 
in  a  person  ?     What  does  a  fine  carriage  and  graceful  walk  indicate  ? 

31.  What  usually  accompanies  any  external  deformity? 


CHAPTER  XI 

THE  BODY  IN  MOTION 
/ 

THE  living  machinery  by  means  of  which  all  the 
movements  of  the  body  are  made  is  the  muscular 
system.  Every  movement  of  a  living  creature  is  made 
by  means  of  muscles.  The  flight  of  a  bird  in  the  air, 
the  rapid  moving  of  an  insect's  wings,  the  gliding  of  a 
snake  along  the  ground,  —  all  animal  movements  of 
whatever  kind  are  made  by  muscles. 

Without  the  muscles,  man,  if  he  could  live  at  all, 
would  be  quite  unable  to  express  his  thoughts  or  feel- 
ings or  to  communicate  them  in  any  way.  Why  ? 
Even  those  changes  of  the  features  which  we  call 
expression  are  due  to  the  play  of  the  delicate  muscles 
of  the  face,  which  by  their  action  pull  the  skin  of  the 
face  about  this  way  or  that,  as  may  be  necessary  to 
express  thoughts  and  feelings.  The  fine  tones  of  the 
orator,  the  pleasing  notes  of  the  singer,  the  marvel- 
ous skill  shown  in  piano  playing,  in  drawing,  and  in 
various  arts,  all  depend  partly  upon  the  action  of  the 
muscles.  This  is  true  of  a  large  part  of  all  the  ex- 
periences of  human  life. 

There  are  two  kinds  of  muscles  in  the  human  body, 

191 


192 


THE  BODY  IN  HEALTH 


those  which  are  under  the  control  of  one's  will,  called 
voluntary  muscles ;  and  the  involuntary  muscles 
Kinds  of  which  one  can  not  control  by  just  willing 
muscles,  to  £Q  so  pjve  hundred  pairs  of  voluntary 
muscles  are  the  servants  of  one's  will  in  performing 
the  different  kinds  of  work  of  which  the  body  is  ca- 
pable. The  number  of  the  involuntary  muscles  is  too 
great  to  be  estimated.  The  skin  is  a  perfect  network 

of  little  mus- 
cles. Every 
hair  has  a 
minute  muscle 
attached  to  it 
by  means  of 
which  it  may 
be  made  to 
stand  erect. 
The  stomach  is  a  muscular  sac,  the  intestines  a  mus- 
cular tube,  the  air  tubes  of  the  lungs  have  muscular 
walls,  and  the  heart,  the  great  pumping  organ  of  the 
circulation,  is  a  wonderful  muscular  engine. 

All  these  involuntary  muscles  act  according  to  the 
needs  of  the  body  and  quite  independent  of  one's  will. 
They  are  at  work  for  us  when  we  are  asleep,  as  well 
as  when  we  are  awake,  keeping  the  heart  beating  and 
the  lungs  active.  When  food  is  swallowed,  it  is  seized 
by  the  involuntary  muscles  and  carried  into  the  stomach, 
worked  upon,  and  moved  from  point  to  point  until  it 
is  digested.  By  means  of  these  muscles,  the  blood  is 


MUSCLES  HAVE  DIFFERENT  SHAPES. 
I,  feather;  2,  spindle;  3,  fan;  4,  ring-shaped. 


THE   BODY  IN  MOTION  193 

circulated  and  the  supply  to  each  part  is  regulated. 
All  their  work  is  done  with  faithfulness  and  loyalty  to 
the  well-being  of  the  body,  even  when  the  voluntary 
muscles  controlled  by  the  will  are  working  against  the 
body's  interests.  Think  of  some  instances  that  will 
illustrate  this. 

The  muscles  are  of  different  shapes  and  sizes,  accord- 
ing to  the  work  for  which  they  are  designed.  Some 
are  shaped  like  a  spindle,  some  like  a  feather,  some 
like  a  fan,  and  still  others  are  ring  shaped. 

The  cells 
which  compose 
the  voluntary 
muscles  are  the 
largest  and  most 

,  MUSCLE  FIBERS. 

active  in  the  en- 
tire body.  They  are  called  muscle  fibers,  because  they 
are  long,  slender,  and  threadlike.  They  have  the  power 
to  contract,  or  draw  themselves  up  as  a  worm  does 
in  crawling,  so  that  they  become  shorter  and  thicker. 
These  muscle  fibers  are  held  together  by  a  sheath 
of  connective  tissue,  which  divides  the  cells  into 
groups  and  ties  them  up  into  bundles. 

The  lean  part  of  meat  is  muscle.  A  piece  of  lean 
corned  beef,  boiled,  may  be  easily  separated  into  small 
bundles.  These  bundles  may,  by  the  use  of  needles, 
be  separated  into  bundles  still  smaller.  These  last 
small  threads  are  the  muscle  fibers. 

Nearly  all  the  voluntary  muscles  are  attached  to 


194 


THE  BODY  IN  HEALTH 


How 
muscles 
are 

attached 
to  bones. 


'—Point  of  Origin 
of  the  Muscle. 


The'Belly  of 
the  Muscle. 


the  framework  of  the  body,  the  skeleton,  because  the 
bones  are  the  levers  by  means  of  which  move- 
ments are  made.  Each  muscle  is  usually 
attached  at  two  points.  The  point  which  is 
less  movable,  or  which  is  nearest  the  center  of 
the  body,  is  called  the  origin,  and  the  other  the 
insertion.  At  the  end  of  each  muscle,  a  continuation 

of  the  connective  tissue  sheath 
is  joined  to  the  periosteum,  thus 
attaching  the  muscle  to  the  bone. 
Nearly  every  muscle  is  joined 
in  this  way  to  two  separate 
bones,  passing  over  the  joint ; 
so  the  muscles  are  an  important 
means  of  holding  the  bones  of 
the  skeleton  together. 

The  connective  tissue  does 
not  always  pass  directly  from 
the  muscle  into  the  periosteum. 
Sometimes  the  tissue  forming  the 
sheath  unites  at  one  or  both  ends 
to  form  a  white  cordlike  struc- 
ture called  a  tendon,  by  means 
of  which  it  is  attached  to  the 

bone.  Some  muscles  have  tendons  at  each  end,  some 
at  the  point  of  insertion  only,  and  still  others  have 
none  at  all. 

Sometimes  the  point  of  insertion,  or  the  place  where 
the  tendon  is  attached  to  the  bone,  is  at  some  distance 


THE   BODY  IN  MOTION  195 

from  the  muscle  itself.  If  all  the  muscles  necessary 
to  give  to  the  hand  its  strength  and  variety  of  move- 
ment were  attached  directly  to  the  bones  of  the  hand, 
it  would  be  very  heavy  and  clumsy.  The  hand  and 
the  foot  are  moved  by  muscles  in  the  arm  and  leg,  to 
which  they  are  attached  by  long,  slender  tendons. 
Why  ?  When  the  hand  is  opened  and  closed,  the 
tendons  which  attach  the  fingers  to  the  arm  muscles 


I 


•    m 


WHY    DO    THE    MUSCLES    STAND    OUT    SO    CLEARLY   IN   THE   ARMS    AND    BACKS    OF 

THESE    BOYS  ? 

may  be  seen  in  the  wrist,  and  the  movements  in  the 
muscles  in  the  arm  may  be  distinctly  felt. 

It  is  of  more  importance  to  us  to  know  how  muscles 
act  and  what  are  the  relation  of  their  action  to  How 
the  work  and  needs  of  life  than  to  know  the  muscles 
particular  names  that  have  been  given  to  the  act 
muscles   and   to  the   bony  parts   to  which  they   are 
attached. 

When   the   cells   of  a   muscle   contract,    the   whole 


196 


THE   BODY  IN  HEALTH 


muscle  is  shortened.  In  shortening,  each  fiber  thickens, 
so  that  there  is  no  change  in  the  actual  size  of  the 
muscle  but  only  in  its  form.  The  shortening  of  the 
muscle  causes  it  to  pull  upon  the  bone  to  which  it  is 
attached,  and  this  results  in  the  bending  of  the  joint 
over  which  the  muscle  passes,  and  a  movement  of  some 
part  of  the  body.  You  can  easily  see  all  this  for  your- 
self by  placing  your  hand  upon  the  large  muscle  in  the 

upper  arm  (bi- 
ceps) and  noticing 
the  shortening 
and  thickening  of 
the  muscle  by 
means  of  which 
the  arm  is  bent 
at  the  elbow  when 
the  hand  is  raised. 
The  muscles 
can  by  their  con- 
traction only  pull 
on  the  bones.  The  biceps  muscle  can  pull  up  the  fore- 
arm, but  it  cannot  push  it  back  into  place.  It  has  to 
be  pulled  back  by  another  muscle.  If  you  bend  your 
arm  at  the  elbow  and  place  your  hand  upon  the  back 
of  the  upper  arm  while  you  straighten  it  out  again, 
you  will  feel  the  tightening  of  the  triceps  muscle  which 
pulls  down  the  forearm  and  holds  it  in  place. 

A  great  many  of  the  voluntary  muscles  are  arranged 
in  pairs  of  antagonistic  muscles,  working  against  each 


ANTAGONISTIC  MUSCLES  IN  THE  ARM. 

I,  biceps;    2,  triceps.     Point  out  the  biceps  and 

triceps  in  the  picture  of  the  boys  on  page  195. 


THE   BODY  IN  MOTION  197 

other  in  the  way  the  biceps  and  triceps  do.  Antago- 
nistic muscles,  with  their  steadying  pull,  one  against  the 
other,  act  as  brakes  which  keep  the  movements  from 
being  jerky  and  spasmodic,  as  they  otherwise  would 
be.  Most  of  the  movements,  as  those  of  the  arms  and 
legs,  —  even  the  simple  act  of  standing  erect,  —  re- 
quire the  action  of  many  muscles,  each  of  which  is 
balanced  by  some  other  one,  thus  enabling  us  to  per- 
form steady  and  graceful  movements. 

If  a  muscle  is  cut,  it  will  immediately   shorten  up 
like  a  piece  of  rubber  on  a   stretch.      The  muscle  is 
always  more  or  less  stretched  or  taut  when  it  Keeping 
is    alive    and    healthy.     This    tension    in   the  muscle 
muscle  is  what  is  called  muscle    tone.     The  i 
muscle  tone  is  kept  up  by  a  stream  of  energy  pouring 
into  it  from  the  nerve  centers.     When  one  is  tired 
out,  this  energy  is  exhausted,  the  muscles  lose  their 
tone,  and  there  is  a  relaxed  condition.     That  is  why  a 
person  who  is  tired  or  weak  lets  his  head  droop  and 
his  chest  collapse.     When  one  goes  to  sleep  in  a  sitting 
position,  the  head  "nods"  or  drops  forward,  because 
the  muscles  that  held  it  in  position  become  relaxed ; 
that  is,  they  lose  their  tone. 

We  can  feel  and  see  the  contraction  of  a  working 
muscle,  but  there  is  another  important  change  taking 
place  in  it  that  we  can  neither  see  nor  feel.  As  the 
muscle  begins  to  contract,  its  arteries  dilate  and  fill 
with  blood,  for  it  is  the  blood  that  brings  to  the  muscle 
the  energy  that  it  requires  for  work.  A  working 


198 


THE   BODY  IN  HEALTH 


muscle  is  warmer  than  one  at  rest,  for  the  reason  that 
muscular  contraction  is  always  accompanied  by  the 
burning  up  of  some  of  the  food  material  which  is  stored 
in  the  muscle  and  brought  to  it  in  the  blood. 

When  any  large  group  of  muscles,  for  instance  those 

in  the  legs,  are 
set  in  active 
operation,  as 
in  jumping  or 
running,  one 
very  quickly 
gets  out  of 
breath.  This 
is  fatigue.  It 
is  due  to  the 
fact  that  when 
the  muscle  is  at 
work,  it  throws 
into  the  blood 
which  passes 
through  it  a 
large  quantity 
of  carbonic  acid  gas,  which  is  poison  to  the  body  and 
must  be  hastened  out  through  the  lungs.  The  greater 
the  amount  of  this  gas  thrown  into  the  blood,  the 
quicker  one  becomes  out  of  breath  and  the  more  rapid 
the  breathing  movements  become.  Then  the  lungs 
are  expanded  to  their  utmost  capacity.  Why  ? 

If  the  exercise  is  less  violent,  but  continued  for  a 


IN     RUNNING    A    LONG    RACE    THE     RUNNERS    DO   NOT 
START   OFF  AT   FULL    SPEED.      WHY? 


THE  BODY  IN  MOTION  199 

longer  time,  one  may  not  get  out  of  breath,  but  after 
a  while  the  muscles  will  become  wearied,  so  that 
movement  is  difficult  and  may  become  impossible. 
This  fatigue,  or  exhaustion,  is  due,  not  to  the  using 
up  of  the  muscle's  store  of  energy,  but  to  the  forma- 
tion of  those  poisonous  substances  that  result  from  the 
muscle  work,  which  we  have  already  studied,  and 
which  have  a  harmful  effect  upon  the  muscle. 

The  muscle  is  a  machine  which  may  be  compared 
to  a  locomotive,  since  it  carries  its  own  fuel.  This 
fuel  is  stored  up  in  the  muscle  in  the  form  of  glycogen, 
or  animal  starch,  which  in  use  is  converted  into  sugar. 
In  work,  the  sugar  is  converted  into  carbon  dioxid 
and  lactic  acid.  These  products  are  muscle  poisons. 
As  work  continues,  the  oxygen  and  glycogen  stored  up 
in  the  muscle  are  lessened  and  the  poisons  accumulate. 
This  hinders  the  muscle  in  its  work.  It  is  in  the 
situation  of  a  locomotive  whose  fire  is  choked  with 
ashes  while  its  fuel  is  low.  This  is  real  fatigue. 

Exertion  may  be  carried  to  such  a  point  that  death 
may  result  from  the  fatigue  induced.  Runners  have 
sometimes  dropped  dead  at  the  end  of  a  long  course. 
Horses  have  been  known  to  die  suddenly  from  the 
same  cause,  as  have  dogs  also  when  attempting  to 
follow  their  master  on  a  long  bicycle  ride.  Carrier 
pigeons  not  infrequently  fall  to  the  ground  dead  from 
exhaustion  after  a  long  and  rapid  flight.  In  such 
cases,  death  is  due  to  the  rapid  accumulation  of  the 
poisons  formed  by  too  prolonged  action  of  the  muscles. 


200  THE   BODY  IN  HEALTH 

It  is  interesting  to  notice  that  exercising  a  part  of 
the  body  may  cause  the  whole  body  to  become  fatigued. 
For  example,  one's  arms  may  become  tired  as  the 
result  of  running.  Show  how  this  can  be  possible. 
How  can  the  poisons  formed  in  the  leg  muscles  get  to 
the  arm  muscles  ? 

Every  movement  of  a  muscle  is  made  in  response 
to  an  impulse  which  it  receives  from  the  nerves.  From 
the  brain  or  the  spinal  cord  a  nerve  goes  to  every 
voluntary  muscle  in  the  body.  Prolonged  muscular 
work  wearies  the  brain  and  nerves,  as  well  as  the 
muscles,  partly  by  reason  of  the  fatigue  poisons  cir- 
culating in  the  blood.  One  is  much  more  likely  to 
become  fatigued  when  performing  exercise  to  which  he 
is  not  accustomed.  Why  ?  When  he  becomes  used 
to  the  work  it  can  be  done  with  less  effort  and  the 
amount  of  fatigue  poison  formed  is  less.  Why  ? 

If  one  who  is  fatigued  will  rest  for  a  time,  the  feel- 
ing of  fatigue  will  probably  disappear.  Rest  generally 
Curing  cures  fatigue  and  puts  the  muscles  in  trim  for 
fatigue.  work  again.  Rest  gives  the  muscle  an  oppor- 
tunity for  increasing  its  store  of  oxygen  and  glycogen 
and  also  for  the  washing  out  by  the  lymph  and  blood 
of  the  poison  with  which  the  muscle  has  been  filled  by 
work. 

A  very  short  hot  bath  will  lessen  fatigue,  because  it 
will  stimulate  the  circulation  of  the  blood  and  so  hasten 
the  removal  of  the  fatigue  poisons.  A  prolonged  hot 
bath  will  aggravate  the  feeling  of  fatigue,  and  it  may 


THE   BODY  IN  MOTION  201 

even  produce  a  feeling  of  exhaustion.  Why  ?  A  short 
cold  bath  will  also  relieve  fatigue  through  its  general 
stimulating  effect  upon  the  body.  One  may  fortify 
himself  against  fatigue  by  cold  bathing,  by  providing 
the  muscles  with  an  abundant  supply  of  muscle  starch 
or  glycogen  and  with  plenty  of  oxygen  by  deep  breath- 
ing of  pure  cold  air. 

After    prolonged    and    violent    exercise,   especially 
exercise  to  which  one  has  not  been  accustomed,  one 
may  find  himself  suffering  from  muscular  sore-  ^^ 
ness  and  stiffness,  together  with  a  feeling  of  effects  of 
great  lassitude.     These  feelings  do  not  usually  fatisue- 
appear  until  some  hours,  perhaps  a  day  or  even  longer, 
after    the    exercise    producing   them.     This    is    called 
secondary  fatigue. 

The  fatigue  caused  by  a  short  period  of  exercise  is 
soon  recovered  from  and  may  disappear  within  a  few 
minutes.  The  longer  and  the  harder  the  work  per- 
formed, the  longer  the  period  of  rest  required.  The 
soreness  and  stiffness  which  accompany  secondary 
fatigue  usually  disappear  in  a  few  days.  Unless  the 
exercise  has  been  exceedingly  violent  so  that  the  parts 
used  have  been  strained  or  injured  in  some  other  way, 
the  muscles  are  then  stronger  than  before  and  able  to 
endure  more  work,  and  the  same  exercise  may  be 
repeated  without  injury.  The  soreness  and  stiffness 
which  follow  the  first  attempts  with  any  new  form  of 
exercise  should  not  discourage  one.  They  should  be 
regarded  as  an  indication  that  Nature  is  preparing  the 


202  THE   BODY  IN  HEALTH 

muscles  for  better  service  by  strengthening  the  mus- 
cular fibers  and  storing  up  a  larger  amount  of  energy. 
Man  is  designed  by  Nature  to  be  the  most  agile, 
enduring,  and  active  of  all  the  members  of  the  animal 
creation.  A  healthy  child  can  with  difficulty  be  re- 
strained from  almost  constant  activity  when  awake. 
The  amount  of  work  which  can  be  performed  by  the 
body  is  much  greater  than  is  usually  supposed.  From 
what  you  have  learned,  should  you  not  say  that  the 
human  body  is  one  of  the  most  perfect  working  ma- 
chines in  existence  ?  It  makes  more  economical  use 
of  the  food  taken  into  it  as  fuel  than  does  the  most 
improved  form  of  locomotive.  The  body  is  able  to 
use  one  fourth  of  its  food  fuel  in  energy,  with  three 
fourths  going  to  the  production  of  heat ;  whereas  the 
most  economical  steam  engine  can  use  only  about 
one  sixth  of  the  energy  of  the  fuel,  with  five  sixths 
being  wasted  as  heat. 

HEALTH  PROBLEMS 

1.  Which  of  your  actions  occur  without  your  knowing  it? 
Was  there  a  time  when  they  would  not  occur  without  your  being 
conscious  of  them  ?     Explain. 

2.  See  if  you  can  locate  in  your  own  body  the  different  shaped 
muscles  referred  to  in  this  chapter.     See  if  you  can  explain  why 
each  muscle  has  the  shape  you  find  it  to  possess. 

3.  Take  a  piece  of  lean  meat  which  has  been  thoroughly  boiled 
and  separate  it  into  muscle  fibers.     Be  careful  that   you  do  not 
stop  with  bundles  of  fibers. 

4.  Point  out  some  muscles  that  pass  over  joints.     Why  do  they 
go  over  the  joints  ? 


THE   BODY  IN  MOTION  203 

5.  See  if  you  can  trace  two  or  three  muscles  from  origin  to  in- 
sertion. 

6.  Locate  some  of  the  tendons  in  your  hands  or  feet  or  else- 
where in  your  body  if  you  think  you  can  find  any. 

7.  Why  did  nature  make  tendons  ?     Why  did  she  not  fasten  the 
muscles  directly  to  the  bone  which  she  wanted  to  move  by  them  ? 

8.  Suppose  the  triceps  in  the  right  arm  be  cut.     How  would 
the  arm  behave  ?     Explain. 

9.  Make  the  experiment  of  closing  your  fist  as  tight  as  you  can 
and  then  opening  it  quickly  and  repeating  with  great  rapidity  as 
long  as  you  can.     Describe  your  experience.     If  you  should  reach 
a  point  when  you  could  not  close  the  fist  longer,  explain  why  this 
should  happen. 

10.  What    kind   of    work   tires    you   most   easily  ?     Explain. 
What  do  you  do  to  get  over  fatigue  ?     Can  you  cure  this  condi- 
tion quite  easily  ? 

11.  Describe  some  experience  of  yours  which  has  made  your 
muscles  stiff  the  day  afterward.     Explain. 

12.  Write  an  essay  on  keeping  the  muscles  in  good  working 
condition. 

REVIEW  QUESTIONS 

1.  What  is  the  living  machinery  in  which  the  movements  of 
the  body  are  made  ? 

2.  Mention  the  various  activities  which  we  can  execute  and 
which  require  the  use  of  the  muscles. 

3.  What  is  meant  by  the  voluntary  muscles  ?      By  the  involun- 
tary muscles  ? 

4.  How  many  pairs  of  voluntary  muscles  are  there  in  the  hu- 
man body  ?     How  numerous  are  the  involuntary  muscles  ? 

5.  What  do  the  involuntary  muscles  do  for  one  that  he  needs  to 
have  done  in  order  to  keep  in  health  ? 

6.  Are  the  involuntary  muscles  more  faithful  than  the  volun- 
tary muscles  ?     Why  ? 

7.  What  are  the  different  shapes  and  sizes  of  muscles  ? 


204  THE   BODY  IN  HEALTH 

8.  Describe  a  muscle  fiber.     How  are  the  muscle  fibers  arranged 
in  the  muscles  ? 

9.  What  part  of  meat  is  usually  composed  of   muscle  fibers  ? 

10.  How  are  the  muscles  attached  to  bones  ?     What  are  the 
names  of  the  points  of  connection  of  muscles  with  bones  ? 

11.  Describe  a  tendon  and  say  for  what  it  is  used. 

12.  Why  did  nature  think  it  necessary  to  make  tendons?     In 
what  parts  of  the  body  may  they  be  felt  by  the  fingers  ? 

13.  What  happens  when  the  cells  of  the  muscles  contract  ? 

14.  How  is  it  possible  that  the  muscles  can  move  a  bone  ? 

15.  Where  is  the  biceps  muscle  ?     Where  is  the  triceps  muscle  ? 

1 6.  Why  are  the  muscles  arranged  in  pairs  working  against 
each  other  ? 

17.  What  will  happen  to  a  muscle  when  it  is  cut  ? 

1 8.  What  does  it  mean  to  keep  up  muscle  tone? 

19.  Explain  why  a  person  who  is  tired  lets  his  head  droop  and 
his  chest  collapse. 

20.  What  change  in  the  character  of  the  blood  takes  place  in  a 
muscle  when  it  contracts  ?     What  is  the  purpose  of  this  change  ? 

2T.   Why  does  one  get  out   of   breath  when  he  is  running  or 
jumping  ? 

22.  What  does  it  mean  to  become  fatigued  ?     Does  one  become 
fatigued  because  his  muscles  wear  out  or  from  some  other  cause  ? 
May  overwork  of  one  muscle  fatigue  the  whole  body  ?     Explain. 

23.  What  may  happen  to  a  person  if  he  exerts  himself  until  he 
is  completely  exhausted  ? 

24.  From  where  do  the  impulses  which  cause  muscles  to  move 
come  ? 

25.  What  kind  of  work  is  likely  to  fatigue  one  most  readily  ? 

26.  What  is  the  best  way  to  relieve  fatigue  ?     What  is  the  value 
of  hot  and  cold  baths  in  relieving  fatigue  ? 

27.  What  causes  secondary  fatigue  ? 

28.  Is  it   truthful  to  say  that  the  human  body  is  the  most 
perfect  working  machine  ever  devised  ? 


CHAPTER   XII 
FEELING  AND  THINKING 

IF  a  community  of  people  are  to  live  and  work  har- 
moniously together,  they  must  have  some  kind  of 
government,  of  course.  The  body  community  must 
also  have  its  government.  The  ruler  of  the  body  is 
the  mind  working  through  the  nervous  system. 

It  is  in  response  to  commands  sent  out  through  the 
nervous  system  that  the  digestive  organs  begin  to 
work  when  food  is  eaten  ;  that  the  lungs  and  heart 
work  faster  to  increase  the  breathing  when  we  run,  so 
that  a  greater  amount  of  oxygen  may  be  carried  to  the 
muscles ;  and  that  the  skin  pours  out  perspiration  to 
cool  off  the  body.  The  nervous  system  brings  all  the 
cells  and  organs  into  communication,  causing  them  to 
work  together  for  the  common  good. 

There  are  two  forms  of  nerve  tissue :  nerve  cells 
and  nerve  fibers.  The  nerve  fibers  are  really  addi- 
tions to  the  cells,  or  parts  of  them.  Most  nerve  cells 
send  out  two  or  three  slender  arms,  one  or  more  of  which 
may  be  prolonged  into  nerve  fibers ;  and  others  con- 
nect with  the  branches  of  other  cells  or  end  in  the 
spaces  between  them.  As  you  see  in  the  pictures,  a 

205 


2O6 


THE   BODY  IN  HEALTH 


nerve  cell  with  its  branches  is  called  a  neuron.     A 
careful  examination  of  the  branches  shows  that  they 

are  covered  with  minute 
buds.  It  is  supposed  that 
these  buds  are  for  the  pur- 
pose of  communicating  di- 
rectly or  indirectly  with 
other  cells. 

The  nerve  cells  are  usu- 
ally found  in  groups,  and 
each  group  has  its  own  par- 
ticular work  to  do  in  the 
government  of  the  body. 
A  group  of  nerve  cells 
having  some  special  work 
is  called  a  nerve  center  or 
ganglion. 

The  little  bundles  of  nerve 
fibers  which  pass  out  from 
a  nerve  center  unite  to  form 
larger  bundles,  which  pass 
to  the  different  parts  of  the 
body.  When  the  body  of 
an  animal  is  dissected,  white, 
glistening  cords  are  found 
running  everywhere  among 
the  tissues.  These  bundles 
of  nerve  fibers  are  called  nerves  or  nerve  trunks. 
There  are  two  divisions  of  the  nervous  system,  just 


Do  YOU  SEE  HOW  THE  MIND  WORK- 
ING THOROUGH  THE  BRAIN,  SPINAL 
CORD,  AND  NERVES  CAN  CONTROL 
ALL  PARTS  OF  THE  BODY  ? 


FEELING  AND  THINKING 


207 


A    NERVE    CELL. 


as  there  are  two  of  the  muscular  system.  All  the  in- 
voluntary muscles,  those  not  under  the  control  of  the 
will,  are  governed  by  what  is  called  the  sympathetic 
nervous  system.  The  voluntary  muscles  are  controlled 
by  the  central  nervous  system. 
The  brain  and  spinal  cord 
are  the  great  centers  of  the 
nervous  system.  In  the  brain 
lies  the  power  by  which  we 
feel,  think,  and  will.  The  brain 
is  simply  an  assemblage  of  nerve  cells  or  neurons, 
hundreds  of  millions  of  them.  With  the  exception 
of  the  whale  and  the  elephant,  the  brain  of  man  is 
larger  than  that  of  any  other  animal. 

The  spinal  cord  enters  the  cranium 
and  connects  with  the  brain  through  a 
large  opening  at  the  base  of  the  skull.  It 
is  a  soft  white  substance,  about  the  thick- 
ness of  a  pencil  or  a  little  thicker.  It 
passes  through  the  backbone,  which  forms 
a  protection  for  it,  and  it  is  also  protected 
by  membranes  like  those  which  cover  the 
brain. 

The  brain  and  the  spinal  cord  send  out  nerves  to  the 
different  parts  of  the  body,  forty-three  pairs  in  all. 
Twelve  of  these  arise  from  the  under  side  of  the  brain 
and  are  called  cranial  nerves.  They  pass  through 
small  openings  in  the  base  of  the  skull  and  are  dis- 
tributed to  the  face,  the  organs  of  sense,  —  eye,  ear, 


A   NERVE    GAN- 
GLION. 


208 


THE   BODY  IN  HEALTH 


nose,  and  mouth,  —  and  to 
the  organs  of  the  chest  and 
abdomen.  Thirty-one  pairs 
of  spinal  nerves  pass  out  from 
the  spinal  cord  through  open- 
ings in  the  side  of  the  spinal 
canal.  The  spinal  nerves  are 
distributed  to  the  trunk  and 
the  extremities  of  the  body. 
•  The  nerves  are  for  the  pur- 
pose of  carrying  messages  be- 
tween the  different 
parts  of  the  body 
and  the  brain  and 
spinal  cord.  The  cell 
branches,  as  well  as  the  mat- 
ter composing  the  center  of 

the  cell,  consist  of  transparent  jellylike  matter  as  clear 
as  water,  yet  possessing  the  most  wonderful  properties 


How  we 
feel  and 
think. 


THE     SYMPATHETIC    NERVOUS     SYS- 
TEM. 


TWO    VIEWS    OF   A    SECTION    OF  THE    SPINAL   CORD. 

of  any  known  substance.  By  means  of  these  living 
threads,  which  are  many  times  smaller  than  the  finest 
spider  web,  the  nerve  cells  of  the  different  parts  of  the 


FEELING  AND  THINKING 


209 


body  are  in  constant  communication  with  one  another, 
just  as  various  points  and  cities  of  a  country  are  in 
communication  by  means  of  telegraph  and  telephone 
wires.  The  brain  is  the  central  office  which  connects 
all  the  different  parts.  If  all  the  other  structures  were 
removed,  —  such  as  the  skin,  bones,  blood  vessels, 
muscles,  —  and  nerve  fibers  and  celk  only  were  Teft, 
the  form  of  the  body  would 
still  be  complete  in  appear- 
ance. What  does  this  sug- 
gest to  you  ?  The  think- 
ing and  feeling  organs,  the 
brain  and  nerves,  really 
occupy  the  whole  body, 
just  as  do  the  circulating 
organs,  the  heart  and  blood 
vessels.  Does  this  mean 
that  there  is  nothing  but 
brain  and  nerves  in  the 
body  ?  What  does  it 
mean  ? 

Experiments  upon  animals  have  shown  that  if  a 
nerve  going  to  any  part  is  cut,  the  application  of 
electricity  to  the  outer  portion  of  the  nerve  will  cause 
the  muscle  to  contract  but  will  not  cause  any  feeling ; 
while  if  electricity  is  applied  to  the  inner  portion  there 
will  be  no  muscular  contraction,  but  a  feeling  of  pain. 
This  experiment  shows  that  nerve  trunks  are  made  up 
of  two  kinds  of  nerve  fibers,  one  carrying  impressions 


A  NERVE  CELL  FROM  THE  SPINAL  CORD 
(MUCH  ENLARGED),  SHOWING  THE 
NUCLEUS. 


2IO 


THE  BODY  IN  HEALTH 


Ingoing 
and  out- 
going 
nerves. 


inward  to  the  brain,  and  the  other  carrying  impulses 
or  commands  outward  to  the  muscles,  or  other  organs. 
The  nerve  fibers  which  carry  impressions  or  sensa- 
tions inwards  are  called  sensory  nerves,  while  those 
which  carry  commands  or  impulses  outwards 
and  cause  all  the  different  motions  of  the  body, 
are  called  motor  nerves.  In  the  spinal  nerves, 
the  sensory  and  the  motor  fibers  are  generally 
bound  together  in  the  same  bundle.  Most  of  the  cranial 

nerves  are  com- 
posed exclusively 
of  either  sensory 
or  motor  nerves. 

Think  of  the 
different  kinds  of 
sensations  which 
you  experience 
and  see  how  many 
you  can  enumer- 
ate. Besides  the 
special  senses, -- hearing,  seeing,  smelling,  tasting,  and 
feeling, — we  have  what  are  called  general  sensations, 
such  as  fatigue,  hunger,  thirst.  You  will  see  that  the 
sensory  nerves  are  of  many  different  kinds.  For  each 
kind  of  sensation,  there  is  in  the  brain  a  special  group 
of  cells  or  a  nerve  center  having  charge  of  that  par- 
ticular sense,  as  you  can  see  in  the  picture. 

The  motor  nerves,  or  nerves  of  work,  are  also  con- 
nected with  different  groups  of  cells  in  the  brain,  each 


A   SPINAL   NERVE 

I,  posterior  root;  2,  posterior  root  ganglion; 
3,  anterior  root. 


FEELING  AND  THINKING 


211 


of  which  has  charge  of  some  particular  organ  or  class 
of  organs.  The  muscles,  the  stomach,  the  liver,  the 
kidneys,  and  all  other  important  organs  have  each 
their  controlling  centers. 

It  is  not  easy  to  comprehend  the  exact  manner  in 
which  impressions  are  carried  by  the  nerves.  The 
best  way,  per- 
haps, is  to 
compare  the 
process  roughly 
to  the  action 
which  passes 
along  a  row  of 
bricks  set  on 
end  in  such  a 
way  that  when 
a  brick  falls 
over  it  will 
strike  the  one 
next  to  it,  which 
in  turn  will  fall 
against  the  next,  and  so  on  to  the  end  of  the  line.  No 
matter  how  great  the  length  of  the  line,  the  impulse  given 
to  the  first  brick  will  be  sent  through  all  the  bricks  to 
the  last.  If  we  imagine  the  line  of  bricks  to  be  a  nerve 
fiber,  with  one  end  in  the  skin  and  another  connected 
with  a  cell  in  the  brain,  we  may  get  some  idea  of  how 
an  impression  may  be  conducted  along  a  nerve. 

(i)  The  large  mass  of  nerve  tissue  which  fills  the 


LOOKING  AT  THE  RIGHT  SIDE  OF  THE  BRAIN. 
I,  cerebrum;  2,  cerebellum;  3,  medulla. 


212 


THE   BODY  IN  HEALTH 


upper  part  of  the  skull  is  called  the  cerebrum.  It 
The  brain  makes  up  three  fourths  of  the  entire  brain 
parts  and  and  is  sometimes  called  the  large  brain,  to 
their  work,  distinguish  it  from  the  cerebellum,  which  is 
sometimes  called  the  small  brain. 

The  cerebrum  is  divided  into  two  hemispheres,  the 
right  and  the  left.  The  surface  presents  many  furrows 

and  folds,  called  convolutions. 
The  outside  is  covered  with  layers 
of  nerve  cells,  which  give  it  a 
gray  color.  It  is  this  gray  mat- 
ter of  the  brain  with  which  one's 
mind  is  chiefly  associated.  Un- 
derneath the  gray  matter  the 
brain  is  white  in  appearance  and 
is  composed  of  the  nerve  fibers 
which  connect  with  the  cells. 
A  network  of  fibers  connects  the 
different  parts  of  the  cerebrum, 
and  countless  fibers  pass  into  the 
spinal  cord. 

The  cerebrum  is  used  in  all  our  thinking.  Through 
the  nerve  messages  which  come  to  it  from  all  parts  of 
the  body,  it  receives  the  sensations  of  light,  heat,  sound, 
smell,  taste,  and  others.  It  also  sends  out  the  mes- 
sages that  cause  voluntary  movement.  Every  part  of 
the  muscular  system  is  connected  with  the  brain ;  and 
each  group  of  muscles  has  a  corresponding  group  of 
cells  by  which  it  is  controlled. 


THERE  ARE  TWO  HALVES  TO 

THE  BRAIN.  You  ARE 
LOOKING  DOWN  ON  TOP  OF 
THE  BRAIN  NOW. 


FEELING  AND  THINKING  213 

When  the  cerebrum  is  removed  from  the  brain  of  an 
animal,  it  does  not  die  at  once,  but  a  remarkable 
change  takes  place  in  it.  If  it  be  a  frog,  it  will  swim 
when  placed  in  water,  and  hop  when  pinched  or  stimu- 
lated in  any  way.  In  this  respect  it  appears  like  any 
other  frog.  But  it  seems  to  have  no  sense.  It  is,  in 
fact,  quite  idiotic.  If  made  to  hop,  it  will  hop  into 
the  fire  as  readily  as  anywhere.  If  left  alone,  it  will 
remain  without  stirring  until  it  perishes.  It  has  no 
power  to  issue  commands.  It  can  perform  only  those 
reflex  actions  which  require  no  intelligence  but  which 
are  the  response  to  some  outside  stimulus.  Why  can 
it  perform  such  acts  but  not  those  requiring  intelli- 
gence ? 

Disease  of  this  part  of  the  brain  in  human  beings 
weakens  the  intelligence.  It  has  been  observed  that 
the  larger  the  cerebrum  in  proportion  to  the  rest  of  the 
brain,  the  greater  the  intelligence  of  the  animal.  It 
is  proportionately  larger  in  man  than  in  any  other 
animal. 

(2)  Beneath  the  back  part  of  the  cerebrum  is  the 
cerebellum,  or  little  brain.  It  is  similar  in  form  to 
the  cerebrum,  and  like  it  is  divided  into  a  right  and 
left  half.  It  is  also  covered  with  a  layer  of  nerve 
cells. 

When  the  cerebellum  is  removed  from  birds  or 
animals,  they  lose  the  power  to  make  regular  move- 
ments. A  man  whose  cerebellum  is  injured  staggers 
about  as  though  intoxicated.  The  movements  are 


2i4  THE   BODY  IN  HEALTH 

jerky  and  overdone.  A  person  who  is  intoxicated  can 
not  walk  steadily,  because  of  the  paralyzing  effect  which 
alcohol  has  upon  the  cerebellum.  So  it  seems  that  the 
chief  office  of  the  cerebellum  is  to  regulate  and  coordinate 
the  movements  of  the  muscles,  and  to  keep  a  proper 
balance  of  the  body  by  causing  them  to  act  in  harmony. 

(3)  The  medulla  is  an  expansion  of  the  upper  end  of 
the  spinal  cord.     It  contains  many  nerve  fibers  which 
connect  the  higher  parts  of  the  brain  with  the  spinal 
cord  and  the  body.     It  is  a  center  for  reflex  and  auto- 
matic actions,  especially  those  which  are  of  the  greatest 
importance  to  the  body,  such  as  the  beating  of  the 
heart  and  breathing. 

We  have  seen  that  life  may  continue  although  the 
cerebrum  or  cerebellum  are  injured  or  even  removed. 
But  the  mere  puncture  of  the  medulla  with  a  needle  is 
sufficient  to  cause  death,  because  it  stops  the  breath- 
ing. For  this  reason  the  medulla  has  been  called  the 
"vital  knot." 

(4)  The  work  of  the  spinal  cord  is  the  same  as  that 
of  the  medulla.     It  is  the  passage  through  which  im- 
pulses are  conducted  to  and  from  the  brain.     It  is 
also  the  center  for  reflex  actions.     If  the  spinal  cord 
is  cut  across  or  severely  injured,  all  parts  of  the  body 
below  the  injury  are  paralyzed,  and  lose  their  feeling, 
because  they  have  lost  their  connection  with  the  cere- 
brum, the  seat  of  feeling  and  of  action.     But  reflex 
actions  are  still   possible.     For   instance,  a  hot   iron 
applied  to  the  foot  will  produce  no  pain,  even  though 


FEELING  AND  THINKING 


215 


the  foot  may  be  severely  burned.  But  if  the  sole  of 
the  foot  is  tickled,  it  will  be  jerked  away  by  a  strong 
contraction  of  the  muscles,  although  the  person  may 
not  even  know  that  his  foot  has  moved.  The  feet  of  a 
person  who  is  sound  asleep  will  move  in-  the  same 
manner  when  tickled.  This  shows  clearly  that  the 
spinal  cord 
without  the 
aid  of  the  brain 
can  carry  on 
reflex  actions 
for  those  parts 
of  the  body 
that  are  sup- 
plied by  the 
spinal  nerves. 

For  this  reason      TRACE  THE  COURSE  OF  THE    PAIN  OF  THE   CANDLE  TO 

r  .     ,  THE     SPINAL     CORD     (l),    THEN    THROUGH    THE     NERVE 

a  frog  without       (a)  T0  THE  MUSCLE  (3). 

a  head  may  be 

made  to   hop,   or   a  headless   turtle   to  walk   about. 

It  does  this  by  means  of  the  spinal  cord. 

When  the  hand  comes  in  contact  with  a  hot  object, 
it  is  instantly  drawn  away.      One  does  not  have  to 
say   to   oneself,    "My   hand    is   likely  to  be  Reflex 
burned,  so  I  had  better  draw  it  away."    The  action- 
hand  is  pulled  away  before  there  has  been  time  for 
thought.     In  a  little  baby  with  no  power  to  reason  the 
hand  would  instantly  be  pulled  away  from  a  candle  flame. 
When  a  sensation  gives  rise  to  motion  in  this  way,  the 


216  THE   BODY  IN  HEALTH 

action  is  called  reflex.  Reflex  actions  are  of  immense 
importance  in  protecting  the  body  from  injuries  of 
various  sorts.  The  acts  of  winking,  swallowing,  sneez- 
ing, coughing,  and  vomiting  are  all  reflex.  These  are 
helpful  movements  ;  and  the  impulse  to  perform  them 
may  be  so  violent  that  it  cannot  be  suppressed  by  the 
will.  Sneezing,  for  example,  is  for  the  purpose  of 
discharging  some  offending  object  from  the  nose; 
coughing  for  removing  some  object  from  the  air  pas- 
sages ;  vomiting  to  empty  the  stomach  of  something 
that  needs  to  be  got  rid  of.  The  closing  of  the  eyelid 
when  the  eye  is  touched  is  another  example  of  reflex 
action.  The  internal  organs  are  controlled  almost 
entirely  by  such  action.  Even  during  sleep,  the 
reflexes,  as  they  are  called,  are  still  active,  drawing 
up  the  foot  when  the  sole  is  lightly  touched  or  pulling 
away  the  hand  if  pricked. 

Besides  these  natural  reflex  actions  requiring  no 
intelligence,  there  are  what  are  called  acquired  reflexes. 
Acquired  Take  the  act  of  walking,  for  example.  When  a 
reflexes.  child  first  attempts  to  walk,  a  voluntary  effort 
is  required  each  time  the  foot  is  moved  and  put  for- 
ward. After  a  while  he  can  walk  a  long  distance  with- 
out thinking  about  it  or  giving  any  attention  to  the 
feet.  The  mind  may  be  wholly  occupied  with  some- 
thing else.  The  action  has  then  become  reflex;  it 
does  itself  without  any  effort  of  the  mind.  This  is 
true  only  when  one  walks  at  his  usual  pace.  If  you 
try  to  walk  much  slower  or  much  faster  than  usual, 


FEELING  AND  THINKING  217 

you  will  find  that  you  have  to  make  a  constant  effort 
to  do  so. 

Writing  is  at  first  a  laborious  act,  which  requires 
very  close  and  constant  effort  to  direct  the  muscles 
employed.  But  the  accomplished  penman  is  able  to 
write  rapidly  without  seeming  to  give  any  thought  to 
the  formation  of  the  letters.  He  thinks  of  the  word 
he  wishes  to  write  and  his  hand  produces  it.  In 
swimming,  bicycle  riding,  piano  playing,  and  many 
other  performances,  the  necessary  movements  are  made 
without  thought,  after  the  nerves  involved  in  them 
have  been  trained  by  practice.  Without  this  arrange- 
ment it  would  not  be  possible  to  become  very  skillful 
in  any  art  or  trade. 

At  the  base  of  the  large  brain  or  cerebrum  are  some 
very  interesting  groups  of  cells  which  serve  as  middle- 
men. They  receive  orders  from  the  large  brain  and 
transmit  them  through  the  spinal  cord  to  the  organs 
for  which  they  are  intended.  Acts  which  are  per- 
formed very  frequently  are  for  the  most  part  passed 
over  by  the  cerebrum  to  these  centers.  They  may 
be  called  the  servants  of  the  cerebrum,  since  they  are 
always  in  waiting  to  carry  out  its  orders  and  at  last 
become  so  well  trained  that  they  can  do  some  kinds  of 
work  without  supervision  of  the  higher  centers.  In 
this  way  the  cerebrum  is  relieved  from  much  labor 
and  drudgery  and  left  free  for  higher  kinds  of  work. 

Each  time  an  act  is  repeated  it  is  done  with  a  little 
greater  ease.  After  a  time  it  is  done  without  any 


2i8  THE   BODY  IN  HEALTH 

effort  of  the  mind.  Then  it  has  become  a  habit. 
"Sow  an  act  and  reap  a  habit ;  sow  a  habit  and  reap 
How  a  character/'  Every  act  of  importance  not 

habits  are  only  originates  in  the  brain,  but  it  makes 
an  impression  upon  it.  It  is  in  this  way  that 
our  characters  are  built.  The  character  is  largely 
formed  by  our  habits.  Perhaps  we  may  say  that  our 
character  is  the  sum  of  all  our  habits,  and  our  habits 
are  formed  by  constantly  repeated  actions. 

One  of  the  most  wonderful  of  the  abilities  of  the  mind 
is  memory.  How  are  sight  pictures  and  sound  pic- 
How  we  tures  stored  in  the  mind,  and  how  are  we  able 
remember.  to  recall  them  ?  In  some  way  impressions 
made  through  the  eye,  the  ear,  and  the  other  senses 
cause  such  actions  and  changes  in  the  nerve  cells  that 
they  are  able  under  the  right  sort  of  conditions  to  call 
back  the  impressions  they  have  received. 

By  means  of  the  delicate  nerve  branches  sent  out  by 
the  cells,  the  cerebrum,  the  seat  of  the  mind,  is  con- 
nected with  other  parts  of  the  brain  in  which  impres- 
sions are  stored.  The  nerve  cells  are  able  to  stretch 
out  or  draw  back  their  branches,  thus  making  or  break- 
ing the  contact  with  other  cells.  The  effort  to  recall 
anything  is  simply  an  act  of  the  will,  stimulating  the 
nerve  cells  and  causing  them  to  stretch  out  their 
branches  in  various  directions.  The  moment  the 
right  contact  is  made,  the  desired  fact  or  picture  will 
flash  into  the  mind.  When  we  are  weary  we  find  it  often 
difficult  to  recall  things  with  which  we  are  quite  familiar. 


FEELING  AND  THINKING 


219 


It  seems  that  then  the  nerve  cells  can  not  make  the 
desired  contacts  with  other  groups  of  cells. 

In  order  for  a  thing  to  be  remembered  it  is  neces- 
sary that  the  first  impression  shall 
be  clear  and  strong.  Whether  an 
impression  lasts  or  not  depends 
mainly  upon  how  clear  it  is.  For 
this  it  is  necessary  that  the  atten- 
tion should  be  concentrated  while 
the  thing  is  being  learned.  Good 
attention  is  the  first  essential  of  a 
good  memory.  The  more  active 
the  mind  is  in  regard  to  any  im- 
pression when  it  is  being  made,  the 
longer  it  is  likely  to  be  retained. 

Exercise   is   quite   as   necessary 
for   the  health  of  the    brain   and 
nerves    as    for    the    rest  How  to 
of    the     body.      Mental  have  a 
strength     and     capacity  clearhead- 
are   developed   by    mental    work, 
just  as  the  muscles  are  developed    THE 
by  muscular  work.     So,  too,  the 
brain    may   be    injured   by   over- 
study,  just   as   may   the   muscles 
be  hurt  by  overstrain. 

When  the  brain  is  weary,  impressions  made  upon  it 
are  slight  and  soon  become  indistinct.  .  For  this  reason 
it  is  not  best  to  spend  more  than  two  or  three  hours  at  a 


...A 


BRANCHES  OF  THE 
NERVE  CELLS  B  AND  C 
ARE  STRETCHED  OUT  TO 
RECEIVE  A  MESSAGE  COM- 
ING FROM  THE  CELL  A. 


220  THE  BODY  IN  HEALTH 

time  in  hard  study  without  rest.  A  short  period  of 
exercise,  especially  if  taken  in  the  open  air,  will 
refresh  the  brain  and  make  it  active  and  ready  to 
receive  new  impressions. 

Muscular  exercise  is  of  great  benefit  to  brain  workers. 
We  have  seen  how  exercise  keeps  the  stream  of  life 
fresh  and  pure  and  washes  away  the  poisonous  products 
that  tend  to  clog  the  mental  machinery.  Students  and 
professional  men  break  down  much  more  often  through 
neglecting  to  take  muscular  exercise  than  through 
doing  too  much  mental  work. 

Plenty  of  fresh  air  and  good  food  are  needed  for  the 
support  of  the  brain  and  nerves,  just  as  for  the  rest  of 
the  body.  Eating  too  much  or  living  on  unwholesome 
or  indigestible  food  clogs  and  hinders  the  brain  in  its 
work.  Clear  thinking  and  a  good  memory  can  go  on 
only  in  a  healthy  and  unclouded  brain.  Overeating 
and  indigestion  are  especially  likely  to  weaken  the 
memory  and  to  produce  a  state  of  mental  confusion, 
lack  of  power  to  concentrate  the  mind,  and  inability  to 
decide  questions. 

Do  you  think  an  abundance  of  sound  sleep  is  neces- 
sary for  the  health  of  the  nervous  system  ?  Why  ? 
During  perfectly  sound  sleep,  the  brain  is  wholly  inactive. 
The  blood  is  drawn  away  to  other  parts  of  the  body, 
the  spaces  about  the  nerve  cells  are  filled  with  lymph, 
and  the  parts  worn  by  use  undergo  repair.  During 
the  activity  of  the  day  there  is  little  opportunity  for 
the  repair  of  brain  tissue.  This  work  is  done  almost 


FEELING  AND  THINKING  221 

wholly  during  sleep.  It  is  then  that  the  cells  of  the 
brain  and  other  nerve  centers  accumulate  a  new  store 
of  energy.  At  least  seven  or  eight  hours  of  sleep  are 
required  daily.  Children  and  young  persons  require 
more  than  older  persons. 

During  unsound  sleep  the  brain  is  partly  active  but 
in  an  irregular  way.  Confused  pictures  present  them- 
selves. The  result  is  dreaming.  When  one  constantly 
dreams  at  night  of  the  work  he  has  been  doing,  it  is  an 
indication  that  those  parts  of  the  brain  used  during  the 
day  are  not  being  properly  rested  and  restored  at  night. 
They  are  in  danger  of  becoming  diseased.  A  vacation 
or  change  of  occupation  is  then  necessary.  Sleepless- 
ness is  often  caused  by  eating  late  in  the  evening.  To 
secure  sound  sleep  it  is  best  to  take  only  ripe  fruit  or 
other  very  easily  digested  food  for  the  evening  meal. 
Tea,  coffee,  and  chocolate  produce  sleeplessness. 

Fatigue  produced  by  exercise  out-of-doors  has  a  won- 
derful effect  in  causing  sleep.  A  prolonged  bath,  from 
fifteen  to  twenty  minutes,  at  a  temperature  of  92  to 
95  degrees,  taken  just  before  going  to  bed,  is  an  excellent 
remedy  for  sleeplessness. 

We  have  already  seen  the  effect  of  alcohol  in  paralyz- 
ing the  nerve  cells  that  control  the  movements  and  so 
causing  a  staggering  walk  and  falling.      Alcohol   also 
makes  a  man  temporarily  insane,  by  paralyz-  Nerve 
ing  certain  of  the  nerve  cells  so  that  the  brain  poisons, 
is  unable  to  make   correct  judgments,     Peculiar  and 
unnatural  combinations  of  ideas  are  made,  often  with 


222  THE  BODY  IN  HEALTH 

terrible  results.  A  man  who  is  naturally  peaceable 
may  while  under  the  influence  of  alcohol  become 
violent,  destructive,  and  ferocious.  In  the  disease 
caused  by  alcohol,  called  delirium  tremens,  the  drunk- 
ard's ideas  become  curiously  mixed.  The  sufferer  sees 
snakes,  reptiles,  and  all  sorts  of  monsters  and  strange 
shapes  before  him. 

The  ill  effects  of  tobacco  upon  the  nervous  system 
have  been  pointed  out  by  many  eminent  physicians. 
Here  are  some  of  the  things  they  say  about  it :  - 

"Giddiness  is  a  common  effect  of  excessive  tobacco 
smoking.  Tremor  is  one  of  the  commonest.  It  may 
be  got  rid  of  entirely  by  leaving  off  the  tobacco." 

"Sleeplessness  is  one  of  the  most  common  effects  of 
tobacco  smoking." 

It  has  been  shown  that  tobacco  poison  affects  the 
auditory  nerve  and  so  causes  defective  hearing  or  deaf- 
ness. 

"The  use  of  ^cigarettes  has  an  evil  effect  upon  the 
mucous  membrane  lining  of  nose  and  throat,  and  as 
these  organs  are  closely  connected  with  the  organ  of 
hearing,  anything  that  affects  them  is  likely  to  react 
upon  the  hearing." 

Tobacco  also  affects  the  optic  nerve  and  so  blunts  the 
power  of  color  perception  and  affects  the  sight  in  other 
ways.  This  is  recognized  in  every  trade  or  profession 
that  requires  quick  and  accurate  sight. 

A  certain,  railway  company  issued  the  following 
notice  to  employees  :  "For  the  betterment  of  the  service 


FEELING  AND  THINKING  223 

and  the  safety  of  the  public  it  will  from  this  date  be  the 
policy  of  this  company  NOT  to  retain  in  its  employ  men 
who  use  intoxicating  liquors  or  cigarettes." 

Tobacco  has  also  a  most  marked  effect  upon  the  mind, 
especially  of  young  smokers.  Out  of  2,336  cigarette 
smokers  who  were  attending  public  school,  only  six 
were  reported  as  "bright  students."  A  very  few  were 
"average."  All  the  rest  were  "poor"  or  "worthless" 
students. 

Its  effects  upon  the  moral  nature  are  even  more 
marked.  A  physician  who  has  had  the  best  oppor- 
tunities for  seeing  the  effects  of  tobacco  upon  the 
morals  says :  "  I  speak  from  a  personal  knowledge  of 
scientific  truth.  The  smoke  is  inhaled  into  the  lungs, 
the  poisonous  gases  are  communicated  through  the 
blood  to  the  brain  and  to  the  nerve  centers  that  control 
the  moral  sensibilities,  stupefying  and  destroying. 
Soon  the  fine  edge  of  the  moral  nature  is  blunted,  and 
the  difference  between  right  and  wrong  is  blurred." 

A  physician  in  an  institution  for  the  insane  says : 
"I  know  whereof  I  speak  when  I  say  that  tobacco, 
when  habitually  used  by  the  young,  leads  to  a  species 
of  imbecility ;  that  the  juvenile  smoker  will  lie,  cheat, 
and  steal,  things  he  would  not  do  had  he  let  tobacco 
alone." 

HEALTH  PROBLEMS 

I.  Suppose  you  should  cut  a  nerve  leading  to  the  end  of  your 
finger  and  you  could  keep  it  from  healing.  What  would  happen 


224  THE   BODY  IN  HEALTH 

to  your  finger  ?  Why  ?  If  you  should  cut  through  the  nerves  on 
one  side  of  your  finger  and  they  should  not  heal,  would  it 
mean  that  you  would  lose  the  part  of  the  finger  below  the  cut  ? 
Explain. 

2.  Does  nature  take  special  pains  to  keep  the  brain  from  be- 
coming injured  ?     If  you  think  so,  give  reasons. 

3.  Why  does  man,  like  most  other  animals,  have  such  a  long 
spinal  column  ?     Why  did  not  Nature  try  to  get  along  without 
a  spinal  column  ? 

4.  Show  just  how  a  command  gets  from  your  brain  down  to  the 
last  joint  in  your  finger,  so  that  you  can  move  it.     How  does  a 
command  travel  down  to  your  big  toe  so  that  you  can  move  it  ? 

5.  What  is  the  meaning  of  the  word  sensory  ?     What  is  the 
meaning  of  the  term  motor  ?     Distinguish  accurately  between  the 
two. 

6.  Show  whether  the  word  cranial  is  a  good  term  for  the  nerves 
to  which  it  is  applied.     In   the  same  way,  show  that  the  term 
spinal  is  a  good  term  for  the  nerves  to  which  it  is  applied. 

7.  Suppose  there  were  no  groups  of  cells  in  the  brain  that  at- 
tended to  special  work  or  controlled  special  organs ;   do  you  think 
a  man  could  then  receive  as  many  impressions  and  do  as  many 
things  as  most  men  can  ? 

8.  Think  of  a  good  way  to  show  that  there  is  a  special  group  of 
cells  in  the  brain  that  has  to  do  with  vision ;   another  group  that 
has  to  do  with  hearing;    another  group  that  controls  the  right 
hand,  and  so  on.     How  do  you  think  people  have  discovered  that 
there  are  special  groups  of  cells  in  the  brain  ? 

9.  Mention  a  number  of  reflex  actions  which  are  not  spoken  of 
in  the  text.     Are  all  the  reflex  actions  you  can  mention  useful  to 
the  person  in  whom  they  occur  ?     Can  you  mention  any  harmful 
reflex  actions  ?     If  so,  how  would  you  control  them  so  that  they 
would  not  get  one  into  trouble  ? 

10.  Mention  some  reflexes  which  you  have  acquired. 

11.  Mention  at  least  five  habits  you  possess  which  are  not 


FEELING  AND  THINKING  225 

mentioned  in  the  text.     Why  is  it  proper  to  speak  of  one's  charac- 
ter as  "the  sum  of  his  habits"  ? 

12.  Can  you  close  your  eyes  and  see  how  your  father,  mother, 
brothers,  and  sisters,  look  ?     Can  you  get  an  image  of  your  break- 
fast table,  so  that  you  can  describe  the  dishes,  the  people  who  sat 
around  the  table,  and  so  on  ? 

13.  Can  you  now  hear  the  voices  of  your  father  and  mother, 
brothers,  and  sisters  even  though  they  are  absent  ? 

14.  What    things    that    happened    last    Fourth    of    July    do 
you  remember  clearly  ?     Explain  why  you   have  not  forgotten 
them. 

15.  Take  something  you  have  forgotten  in  literature,  arithme- 
tic, spelling,  or  any  other  subject,  and  see  if  you  can  tell  why  you 
have  not  .remembered  it.     What  could  you  have  done  so  that  it 
would  have  remained  with  you  ? 

1 6.  Have  you  ever  tried  taking  exercise  when  you  could  not 
learn  rapidly  ?     Has  it  cleared  up  your  mind  ?     If  you  are  tired  and 
take  exercise,  will  it  help  you  in  your  study  ?     Explain. 

17.  What  has  happened  in  the  nervous  system  of  the  person 
who  is  drunk  ?     Suppose  the  alcohol  remained  in  his  system  con- 
tinuously, what  would  become  of  him  ? 

1 8.  Why  does  a  person  who  is  learning  to  smoke  have  headaches, 
vomiting,  and  other  disturbance  ?     What  do  these  disturbances 
show  with  regard  to  Nature's  plan  ? 

REVIEW  QUESTIONS 

1.  Where  do  the  commands  come  from  that  set  the  digestive 
organs  at  work,  that  make  the  lungs  work  faster  when  necessary, 
and  so  on  ? 

2.  What  are  the  two  kinds  of  nervous  tissue  ? 

3.  Describe  the  nerve  cell.     For  what  use  are  the  buds  on  the 
branches  of  nerve  cells  ? 

4.  What  is  a  nerve  center,  or  ganglion  ? 

Q 


226  THE   BODY  IN  HEALTH 

5.  What  are  the  bundles  of  nerve  fibers  called  ? 

6.  What  are  the  two  divisions  of  the  nervous  system  ? 

7.  What  is  the  "  headquarters,"  as  one  might  say,  of  the  nerv- 
ous system  ? 

8.  How  does  the  spinal  cord  connect  with  the  brain  ?     Describe 
this  cord  in  detail  alone,  and  in  connection  with  the  rest  of  the 
nervous  system. 

9.  For  what  are  the  nerves  used  ? 

10.  Of  what  is  the  matter  in  the  center  of  the  cell  composed  ? 

11.  What  are  the  nerves  that  convey  impressions  from  the 
senses  to  the  brain  called  ?     What,  those  that  carry  commands 
from  the  brain  to  the  muscles  ? 

12.  What  are  the  general  sensations  which  the  brain  receives  ? 
What  are  the  special  sensations  ? 

13.  Show  how  impressions  are  conducted  from  nerves  to  the 
brain  or  from  the  brain  to  the  muscles. 

14.  What  is  a  reflex  action  ?     What  is  its  use  ?     Name  some 
reflex  actions  which  may  occur  during  sleep. 

15.  What  name  is  given  to  the  large  brain?     What  name  is 
given  to  the  small  brain  ? 

1 6.  With  what  is  the  outside  of  the  brain  covered  ?     What  is 
its  color  ? 

17.  What  part  of  the  brain  do  we  use  in  our  thinking  ?     Where 
is  this  part  located  ? 

1 8.  What  happens  to  a  frog  when  its  cerebrum  is  removed? 
What  does  this  show  regarding  the  work  of  the  cerebrum  ? 

19.  When  the  cerebellum  is  removed  from  birds  and  animals, 
what  happens  to  them  ? 

20.  Where  is  the  medulla  situated  ?     What  work  does  it  have 
to  perform  ? 

21.  What  is  the  work  of  the  spinal  cord  ? 

22.  Why  can  reflex  actions  occur  when  a  person  cannot  feel 
anything  ? 

23.  How  is  it  possible  for  a  frog  without  a  head  to  hop  ? 


FEELING  AND  THINKING  227 

24.  What  is  the  office  of  the  "  middle  men"  ?     Give  some  exam- 
ples. 

25.  How  does  one  form  habits  ?     What  is  the  relation  between 
habits  and  character  ? 

26.  How  is  it  possible  for  one  to  retain  the  memory  of  any 
experience  he  has  had  ? 

27.  Why  is  it  difficult  to  recall  things  when  one  is  weary  ? 

28.  What  is  necessary  in  order  that  one  should  be  able  to  remem- 
ber anything  ?     How  could  one  cultivate  a  good  memory  ? 

29.  Is  exercise  necessary  for  the  health  of  the  brain  and  nerves  ? 
Why? 

30.  How  can  one  develop  mental  strength  and  capacity  ? 

31.  Why  is  it  not  best  to  study  when  one  is  fatigued  ?     What 
kind  of  exercise  is  good  for  brain  workers  ?     Why  ? 

32.  What  sort  of  habits  will  interfere  with  one's  having  a  clear 
head  ? 

33.  Is  sleep  necessary  for  the  health  of  the  nervous  system? 
Why  ?     What  is  a  good  way  to  overcome  sleeplessness  ? 

34.  Why  does  one  dream  ?     What  kind  of  habits  will  be  likely 
to  make  one  dream  a  good  deal  ? 

35.  Mention  some  nerve  poisons  and  their  effect  on  the  brain 
and  nerves. 

36.  What  do  physicians  say  about  the  effect  of  tobacco  on  the 
nervous  system  ? 


CHAPTER  XIII 
GATEWAYS  OF  THE  MIND  —  SIGHT 

THE  brain  has  only  one  way  of  getting  information 
from  the  outside  world.  This  is  by  means  of  sensations 
received  through  the  nervous  system.  There  are  two 
kinds  of  sensations  :  (i)  Those  which  arise  from  condi- 
tions within  the  body,  such  as  fatigue,  drowsiness,  pain, 
hunger,  and  thirst.  These  are  called  general  sensations. 
(2)  Those  which  are  caused  by  some  stimulus  from  out- 
side, —  sight,  hearing,  smell,  taste,  and  touch,  by  means 
of  which  we  get  a  knowledge  of  objects  in  the  world 
about  us.  These  are  called  the  special  sensations. 

The  special  senses  are  the  avenues  or  gateways  to  the 
mind.  The  information  brought  to  the  brain  through 
them  is  the  food  of  the  mind,  or  thought  material. 

Perhaps  the  most  remarkable  of  these  avenues  to  the 
brain  is  the  eye.  The  eye  is  a  picture-making  instru- 
The  eye  merit,  very  much  like  a  photographer's  camera, 
the  body's  only  much  more  wonderfully  and  perfectly 
made.  The  eye  of  an  ox  recently  killed  may  be 
prepared  in  such  a  way  that  one  can  clearly  see  the  pic- 
ture formed  by  the  lens  of  the  eye  on  the  dark  curtain 
stretched  across  the  back  of  the  eye  globe.  In  some 

228 


GATEWAYS  OF  THE  MIND  — SIGHT        229 


mysterious  way,  by  means  of  the  special  nerve,  the 
optic  nerve,  which  connects  the  eye  with  the  brain,  a 
record  is  made  of  this  picture  in  the  cells  of  the  brain. 

Ingenious  human  inventors  have  labored  for  many 
years  to  solve  the  problem  of  the  sending  of  a  picture 
over  a  telegraph  wire.  Here  we  have  the  thing  done, 
apparently  only  a  bundle  of  minute  white  threads 
running  from  the  brain  to  the  eye,  spread  out  in  a  thin, 
transparent  membrane  over  the 
screen  upon  which  the  picture  is 
formed. 

One  looks  at  an  object :  the 
face  of  a  friend,  a  beautiful  flower, 
a  strange  animal,  a  collision  of 
vehicles  in  the  street.  The  next 
day,  or  it  may  be  years  after, 
the  picture  may  be  reproduced 
in  the  mind,  showing  that  a 

record  has  been  made  in  the  brain.  A  famous  artist 
once  produced  from  memory  a  copy  of  a  picture 
hanging  in  a  gallery  in  a  distant  city.  The  copy  was 
so  like  the  original  that  it  was  difficult  to  distinguish  it 
from  it.  This  is  what  the  brain  is  doing  all  the  time 
for  every  one  who  has  a  healthy  brain  and  eye  and  optic 
nerve. 

The  picture  in  the  eye,  instead  of  being  painted  there, 
as  in  a  photograph,  is  bleached  there  by  destruction  of 
the  coloring  matter  on  the  screen  where  the  rays  are 
focused.  This  produces  a  picture  in  white.  A  chalk 


THE  EYE  IS  A  PICTURE-MAKING 
INSTRUMENT,  SOMETHING 
LIKE  A  PHOTOGRAPHER'S 

CAMERA. 


23o  THE   BODY  IN  HEALTH 

picture  made  upon  a  blackboard  must  be  wiped  off 
before  a  new  picture  can  be  drawn  there.  Otherwise 
the  lines  would  be  mixed  and  the  pictures  indistinct. 
For  this  reason  the  eye  picture  must  also  be  effaced 
before  a  new  picture  is  formed.  This  is  done  by  a 
constant  reproduction  of  the  coloring  matter  to  pre- 
pare a  new  screen  for  every  new  picture.  So  rapidly  is 
this  work  done  that  it  is  possible  for  one  to  form  a  clear, 
distinct  picture  of  a  new  and  separate  object  eight  times 
in  a  second. 

The  eye  is  well  protected  by  nature.  The  eyes  are 
set  in  deep  bony  sockets  in  the  skull,  open  in  front. 
The  pro-  At  the  back  part  there  is  an  opening  through 
tectionof  which  pass  the  nerves  which  connect  the  eye 
the  eye.  with  the  brain.  The  eye  socket  is  lined  with 
fat,  which  forms  a  soft  cushion  for  the  eye  to  rest  and 
turn  on,  and  it  helps  to  protect  the  eye  from  injury. 

The  eyelids,  eyelashes,  and  eyebrows  also  assist  in 
protecting  the  eyes  from  injury.  The  eyelids  protect 
the  eye  from  too  much  light  and  close  down  and  cover 
the  exposed  part  of  the  eyeball  if  a  blow  or  other  injury 
is  threatened.  Along  the  edge  of  the  folds  of  skin  that 
form  the  eyelids  may  be  seen  the  openings  of  numerous 
little  glands  which  pour  out  an  oily  substance  that 
prevents  the  overflow  of  the  tears.  The  eyelashes, 
with  which  the  edge  of  the  lids  is  also  furnished,  keep 
dust  out  of  the  eyes. 

The  little  gland  that  produces  the  tears,  the  lachrymal 
gland,  is  within  the  socket  of  the  eye,  at  the  outer  and 


GATEWAYS  OF  THE   MIND  — SIGHT        231 

upper  side.  A  secretion  is  constantly  being  formed  in 
small  quantities  for  the  purpose  of  moistening  the  eyes. 
This  secretion  is  drained  away  by  means  of  two  little 
canals,  one  at  the  edge  of  each  lid,  at  the  inner  corner  of 
the  eye.  These  little  canals  open  into  a  small  sac  from 

which  the  tears  are  carried 
into  the  nose,  through  a 
duct  called  the  nasal  duct. 
When  the  secretion  from  the 


WHERE  THE  TEARS  ARE  MADE,  AND 

HOW  THEY  ARE  DRAINED  OFF. 

I,  the  nasal  duct;   2,  the  lachrymal 

gland. 


aqueou, 
humor 


'optic  n 
THE    PARTS   OF  THE    EYE. 


lachrymal  gland  is  formed  in  too  great  quantity  to 
be  carried  off  in  this  way,  the  tears  flow  over  the  lids 
and  run  down  the  cheeks. 

Each  eye  is  provided  with  six  little  muscles.      One 
end  of  these  is  attached  to  the  socket  and  the    h 
other  to  the  eyeball.     By  this  means  the  eye  Of  the  eye 
may  be  turned  in  various  directions.     Think  and  their 
what  would  be  the  effect  it  if  were  not  possible  * 
to  move  the  eyeball ! 

The  eyeball  has  three  layers  or  coats :     the  outer 


232  THE   BODY  IN  HEALTH 

coat,  or  sclerotic ;  the  middle  coat,  or  choroid ;  the 
inner  coat,  or  retina. 

The  sclerotic  is  formed  by  a  dense  white  membrane, 
—  the  white  of  the  eye,  as  we  call  it.  In  the  front  of  it  is 
a  transparent  portion  called  the  cornea,  which  lets  the 
light  through  into  the  eye,  just  as  a  window  lets  the 
light  into  a  room. 

Next  to  the  sclerotic  and  in  close  contact  with  it  is 
the  choroid,  which  is  of  a  rich,  purple  color.  In  the 
front  of  the  choroid,  just  at  the  back  of  the  transparent 
cornea,  is  the  iris,  a  movable,  muscular  curtain  lined 
with  dark  pigment.  The  iris  is  the  colored  part  of  the 
eye,  blue,  brown,  gray,  or  black,  which  we  see  through 
the  transparent  cornea.  It  has  in  the  center  an  open- 
ing which  we  call  the  pupil. 

The  iris  regulates  the  amount  of  light  that  enters  the 
eye.  When  the  light  is  dim,  the  opening  is  enlarged  to 
let  in  as  much  light  as  possible.  When  the  light  is 
strong,  the  pupil  is  made  very  small  to  protect  the  eye. 
You  have  seen  the  pupils  in  the  eyes  of  a  cat  in  the  sun- 
light reduced  to  mere  slits,  while  in  one  that  has  been  in 
the  dark  the  pupils  are  so  enlarged  that  the  iris  can 
scarcely  be  seen.  The  pupils  of  the  eyes  of  cats  and 
some  other  animals  can  be  opened  wider  than  the 
human  eye,  so  that  they  can  see  at  night  better  than 
we  can. 

The  retina,  the  inner  coat  of  the  eyeball,  contains  the 
nerves  of  sight.  It  is  formed  by  the  spreading  out 
of  the  optic  nerve,  which  enters  the  eyeball  at  the  back, 


GATEWAYS  OF  THE  MIND  —  SIGHT        233 

nearly  opposite  the  pupil.  It  is  composed  of  several 
layers  of  different  kinds  of  cells,  which  are  connected 
with  the  ends  of  the  fibers  of  the  optic  nerve.  In  this 
way  it  is  connected  with  the  nerve  centers  in  the  brain 
that  preside  over  the  sense  of  sight.  The  layer  of 
cells  next  to  the  choroid  or  middle  coat  has  a  purple 
color.  The  color  fades  when  the  retina  is  exposed  to 
light,  but  is  constantly  reproduced  by  the  choroid. 

Just  at  the  back  of  the  iris  is  the  crystalline  lens, 
which  divides  the  inside  of  the  eye  into  two  chambers. 
The  large  posterior  chamber  at  the  back  of  the  lens 
forms  the  greater  part  of  the  cavity  of  the  eyeball.  It  is 
filled  by  a  transparent,  jellylike  substance  called  the 
vitreous  humor.  The  small  anterior  chamber  in  the 
front  of  the  lens  is  filled  with  the  aqueous  humor,  a 
watery  fluid  which  runs  out  when  the  eyeball  is  pierced 
with  a  sharp  instrument. 

The  lens,  aided  by  the  convex  surface  of  the  cornea, 
forms  images  of  the  objects  that  we  see.  An  image 
formed  by  a  lens  in  the  front  of  a  camera 
may  be  seen  upon  the  ground  glass  at  the  back 
of  the  camera.  If  we  hold  a  convex  lens  be-  images  and 
fore  a  window  and  at  the  proper  distance 
from  a  screen  of  thin  oiled  paper  or  ground 
glass,  we  may  see  upon  the  screen  a  perfect  picture 
of  the  window,  but  much  smaller  than  the  original. 
The  lens  and  the  cornea  of  the  eye  form  images  upon 
the  retina  in  the  same  way  that  the  image  is  formed 
on  the  screen  or  camera. 


234  THE   BODY  IN  HEALTH 

Many  colored  fabrics  fade  or  lose  their  color  when 
long  exposed  to  the  sun's  rays.  Muslin  may  be 
bleached  or  made  white  by  exposure  to  the  sun.  When 
the  retina  taken  from  the  eye  of  an  animal  is  exposed 
to  the  sun  the  color  is  bleached  out  in  the  same  way. 
But  if  it  is  left  in  contact  with  the  choroid,  and  is 
placed  in  the  dark,  it  will  soon  recover  its  color. 

If  we  allow  the  image  formed  by  a  lens  to  fall  upon 
the  retina  taken  from  the  eye  of  an  animal,  the  picture 
will  be  bleached  upon  the  retina  by  the  action  of  the 


THE    FORMATION    OF   AN    IMAGE    ON   THE    RETINA. 

sun's  rays.  This  is  exactly  what  happens  when  we 
see  an  object.  The  lens  of  the  eye,  assisted  by  the 
cornea,  forms  upon  the  retina  an  image  which  is  bleached 
out  in  the  way  described.  The  impression  made  upon 
the  retina  is  carried  to  the  brain  by  means  of  the  optic 
nerve. 

Impressions  made  upon  the  retina  may  last  after  the 
object  making  the  impression  is  removed.  A  thing 
may  be  looked  at  for  only  the  hundredth  part  of  a  second, 
yet  it  will  take  a  whole  tenth  of  a  second  for  the  image 
formed  to  die  away.  You  can  see  that  if  a  second 


GATEWAYS  OF  THE  MIND  — SIGHT        235 

picture  is  presented  before  the  first  has  died  away,  the 
pictures  will  blend.  The  effect  is  then  the  *ame  as  if 
both  objects  were  seen  at  the  same  time. 

A  toy  has  been  made  to  illustrate  this.  It  consists  of 
a  piece  of  white  card  with  two  strings  upon  which  it 
can  be  twirled.  On  each  side  of  the  card  a  different 
picture  is  painted.  Suppose,  for  instance,  that  on  one 
side  of  the  card  is  a  lion  and  on  the  other  his  cage. 
When  the  card  is  rapidly  twirled  by  being  blown  upon, 
the  lion  will  be  seen  in  his  cage.  Or  it  may  be  a  horse 
on  one  side  and  his  rider  on  the  other.  Twirling  the 
card  rapidly  will  have  the  effect  of  seating  the  rider 
upon  his  horse.  Explain  the  principle. 

If  you  examine  carefully  the  image  made  by  a  lens 
you  will  see  that  the  picture  is  inverted,  or  bottom  part 
up.  The  two  sides  are  also  reversed.  This  is  because 
the  rays  of  light  cross  each  other  in  passing  through  a 
lens.  Why  is  it  that  though  the  picture  in  the  eye  is 
upside  down,  yet  we  seem  to  see  the  object  right  side 
up  ?  Do  you  think  the  infant  sees  things  right  side  up 
as  we  do  ? 

By  experimenting  with  a  lens  held  at  a  certain  dis- 
tance from  a  screen,  you  will  see  that  the  images  of 
near  and  of  distant  objects  are  not  equally  Seeing 
perfect.     In  order  to  get  good  pictures  of  all  near  and 
objects,  you  must  either  change  the  position  farobJects- 
of  the  lens,  or  use  a  thicker  lens  for  near  objects  and  a 
thinner  one  for  distant  objects.     The  position  of  the 
lens  in  the  eye  can  not  be  changed.     It  is  fixed  at  a 


236 


THE   BODY  IN  HEALTH 


certain  distance  from  the  retina.     Neither  can  it  be 
exchanged  for  a  thicker  or  thinner  one,  according  to 

the  object  to  be  looked  at. 
But  nature  has  provided  a 
means  by  which  the  lens  may 
be  made  thicker  or  thinner  and 
so  adjust  itself  perfectly  to  see 
objects  at  different  distances. 

SHOWING  CHANGES  IN  THE  LENS    J 

IN  ACCOMMODATION.  This  is  done  by  means  of  the 

muscular  ring  surrounding  the 

lens,  —  the  suspensory  ligament.  This  work  of  adjust- 
ing the  lens  is  called  accommodation.  The  eye  seems 
to  see  without  effort  objects  at 
a  distance,  and  accommodation 
is  exercised  only  for  near  objects. 
A  perfectly  natural  eye  can  not 
adjust  itself  to  see  objects  nearer 
than  five  to  eight  inches. 

In  reading  or  in  doing  any  kind 
of  work  held  near  the  eyes,  the  muscles  of  the  sus- 
pensory ligament  are  contracted  to  thicken  the  lens 

and  so  adjust  it  for  seeing 
near  objects.  If  the  work  is 
long  continued,  these  muscles 
may  become  wearied.  It  is 
a  good  thing  to  relax  these 
A  LONG  EYEBALL.  muscles  and  rest  the  eyes  by 

gazing  out  of  a  window  into  the  distance. 

In  some  persons  the  eyes  are  long  from  the  front  to 


AN     EYEBALL     OF    JUST    THE 
RIGHT    LENGTH. 


GATEWAYS  OF  THE   MIND  —  SIGHT        237 

the  back,  so  that  the  retina  is  farther  than  usual  from 
the  lens.     Here  is  a  little  experiment  which  TWO  kinds 
will  help  you  to  understand  what  effect  this  °fsight- 
has  upon  the  sight. 

Take  a  lens  which  will  make  a  distinct  image  of 
distant  objects  upon  a  screen  held  a  few  inches  behind  it. 
If  the  screen  be  moved  a  little  farther  from  the  lens, 
the  image  of  distant  objects  will  become  indistinct. 
But  if  an  object  is  held  near  the  lens,  a  clear  image  of 
it  will  be  formed  upon  the  screen.  This  shows  us 
that  if  the  retina  of  an  eye  should  happen  to  be  farther 
from  the  lens  than  it  ought  to  be,  distant  objects  would 
not  be  seen  clearly,  although  near  objects  might  be  seen 
distinctly,  even  nearer  than  by  the  ordinary  eye.  A 
person  having  such  eyes  is  said 
to  be  short  sighted. 

In  other  cases  the  eyeball  is 
shorter  than  usual,  so  that  the 
retina  is  brought  too  near  the 
lens.  In  these  cases  distant 

A   SHORT    EYEBALL. 

objects   may   be   clearly   seen, 

while  near  objects  are  blurred  or  indistinct.    Such  eyes 

are  called  long  or  far  sighted. 

If  you  watch  an  elderly  person  trying  to  read  without 
glasses,  you  will  notice  that  usually  the  book  is  held  a 
long  way  from  the  eyes.  The  reason  for  this  is  that  at 
about  the  age  of  forty-five  years  the  lens  begins  to 
harden,  so  that  it  can  not  be  accurately  adjusted  to  near 
objects. 


238  THE   BODY  IN  HEALTH 

In  some  cases  the  curvature  of  the  cornea  is  uneven 
and  some  parts  are  flatter  than  other  parts.  When 
this  irregularity  is  enough  to  distort  the  image  so  that 
objects  are  not  seen  clearly,  it  is  called  astigmatism. 

Near-sighted,  long-sighted,  and  old  persons  need  the 
assistance  of  glasses  which  will  cause  the  image  to  fall 
Wearing  exactly  on  the  retina,  and  so  be  distinctly  seen, 
glasses.  For  a  near-sighted  eye,  in  which  the  rays  of 
light  meet  before  they  reach  the  retina,  concave  lenses 
are  needed  to  spread  the  rays  of  light  farther  apart. 
Far-sighted  eyes,  in  which  the  rays  reach  the  retina 
before  they  meet,  need  convex  lenses,  which  will  bend 
the  rays  of  light  toward  each  other,  and  cause  them  to 
meet  more  quickly.  Old  persons  need  convex  lenses 
which  should  be  changed  as  age  increases.  When  an 
old  person  finds  himself  obliged  to  pull  his  glasses  down 
on  his  nose  in  order  to  see  clearly,  it  is  a  sign  that  he 
needs  a  stronger  pair  of  glasses. 

The  eye  is  the  organ  of  sight,  but  it  is  with  the  brain 
that  we  actually  see.  If  the  optic  nerve  is  cut,  pictures 
With  what  w^  st^l  ^e  f°rmed  in  the  eye  but  there  will 
do  we  be  no  sight.  It  is  with  the  brain  that  we  form 
really  see?  judgments  of  the  images  transmitted  through 
the  eye,  as  to  their  distance,  shape,  position,  solidity. 
The  nerve  centers  controlling  sight  have  to  be 
trained  by  practice  to  form  accurate  judgments.  A 
little  baby  reaches  out  for  everything  it  sees,  no  matter 
how  far  away,  and  experiments  have  shown  that  it  is 
months  before  it  has  a  definite  idea  of  distance.  Why  ? 


GATEWAYS  OF  THE  MIND  —  SIGHT        239 

A  young  Scotchman  who  was  born  blind  received  his 
sight  by  means  of  an  operation  when  he  was  thirty 
years  old.  He  at  first  thought  that  everything  he  saw 
was  quite  close  to  him.  The  first  day  that  he  sat  at  the 
window,  he  put  out  his  hand  to  touch  the  sidewalk, 
which  was  two  stories  below.  He  said,  "The  first  meal 
I  ate  was  an  odd  experience.  When  I  saw  that  great 
hand  with  a  huge  fork  approaching  my  mouth,  the 
impulse  to  dodge  was  almost  irresistible."  Explain 
this  man's  experience. 

The  eyes  are  such  a  precious  possession  that   they 
need  to  be  guarded  carefully.     Think  from  how  much 
one  is  shut  out  who  does  not  have  the  use  of  The  care 
these  wonderful  organs  that  tell  him  of  all  the  of  the 
beautiful  and  interesting  things  in  the  world  eyes" 
around  him.     Carelessness  in  the  use  of  the  eyes  while 
one  is  young  may  cause  a  great  deal  of  trouble .  and 
even  blindness  later  in  life. 

It  is  of  importance  that  the  eyes  should  not  be 
strained.  This  is  most  likely  to  occur  in  reading. 
When  one  is  interested  in  a  book,  it  is  sometimes  a 
temptation  to  go  on  reading  into  the  twilight,  before 
the  lamps  are  lighted.  Reading  in  a  poor  light  is  a 
great  strain  on  the  eyesight.  Why  ?  Reading  very 
fine  print  for  a  long  time  without  resting  the  eyes  also 
strains  them.  Why  ? 

Reading  on  the  cars  is  likely  to  be  injurious  to  the 
eye,  because  of  the  shaking  which  continually  changes 
the  distance  between  the  book  and  the  eye.  You  can 


240  THE   BODY  IN  HEALTH 

see  what  a  tax  this  is  upon  the  muscles  of  accommoda- 
tion, which  must  keep  adjusting  the  eye  to  the  changed 
distance. 

Reading  while  lying  down  is  a  bad  practice.  In  this 
position  too  much  blood  comes  to  the  eyes,  which  are 
likely  to  become  congested.  The  book  is  also  likely  to 


SOME    PEOPLE    HAVE   THE    BAD   HABIT   OF  READING   IN   BED. 

be  held  in  an  awkward  position  which  may  strain  the 
eyes. 

It  is  not  a  good  thing  to  read  when  first  awaking  in 
the  morning,  as  it  takes  a  little  while  for  the  eyes  to 
become  accustomed  to  the  light.  Sudden  exposure  of 
the  eyes  to  very  bright  light  may  be  injurious  for  the 
same  reason. 

The  direction  in  which  the  light  falls  is  of  very  great 


GATEWAYS  OF  THE  MIND  — SIGHT 


241 


importance  to  the  eyes  in  such  occupations  as  reading, 
writing,  and  needlework.  The  light  should  shine  upon 
the  work,  not  upon  the  eyes.  You  may  find  out  for  your- 
self the  best  position  for  doing  near  work  of  any  kind 
by  trying  a  few  experiments.  Sit  or  stand  with  your 
back  to  a  window  while  you  read.  You  will  see  that 


THIS   BOY'S   EYES  WILL   BE   HURT  IF  HE   DOES   NOT  KEEP  THE   BRIGHT  LIGHT 
FROM  SHINING  DIRECTLY  INTO  THEM. 

your  shadow  falls  upon  the  page  and  darkens  it.  Now 
face  the  window,  and  you  will  see  that  this  is  even 
more  unsatisfactory.  The  light  shines  directly  into 
the  eyes,  while  the  book  is  in  shadow.  Standing  with 
your  right  side  to  the  window  you  .will  find  a  great 
improvement.  The  light  now  falls  directly  upon  the 


242  THE  BODY  IN  HEALTH 

page  and  not  upon  the  eyes.  But  try  writing  in  this 
position.  The  hand  then  casts  a  shadow  upon  the 
paper  which  will  obscure  the  light  just  where  it  is  most 
needed.  Stand  now  with  your  left  side  to  the  window, 
and  you  will  find  that  the  light  is  just  right  for  all 
purposes. 

Notice  where  the  windows  in  your  schoolroom  are 


WHICH    OF    THESE    THREE    CHILDREN     HAS    THE     BEST     POSITION     FOR    THE     EYES  ? 
WHICH    THE    WORST    POSITION  ? 

placed  and  how  the  light  falls  upon  your  desk.  Is  it  a 
good  thing  for  the  teacher's  desk  to  be  placed  in  front 
of  a  window  ?  Which  is  the  best  position  for  the  black- 
boards, between  the  windows  or  facing  them  ? 

Severe  headaches,  indigestion,  and  other  nervous 
troubles  may  be  caused  by  defective  eyesight.  If  the 
eyes  become  easily  tired  and  can  be  used  but  a  short 


GATEWAYS  OF  THE   MIND  — SIGHT        243 

time  without  blurring  of  the  vision  or  aching  of  the  eye- 
balls, they  should  be  examined  by  a  specialist,  and  if 
possible,  properly  fitted  with  glasses.  It  has  been  found 
that  from  30  to  60  out  of  every  100  children  in  the  public 
schools  should  wear  glasses. 

The  corners  of  the  eyes  should  be  kept  clean,  and  the 
lids  washed  carefully.  A  disease  which  causes  very  great 
soreness  and  inflammation  of  the  lids  is  due  to  the  grow- 
ing of  germs  inside  the  lining  of  the  eyelids.  It  is  not 
safe  to  use  public  wash  basins  or  towels,  because  of  the 
danger  of  getting  the  eyes  infected  with  these  germs. 
Children  suffering  from  this  disease  are  not  allowed 
to  attend  the  public  schools,  because  of  the  danger  of 
infecting  other  children. 

At  home  as  well  as  at  school  and  wherever  the  person 
is  who  has  a  communicable  eye  disease,  the  greatest 
of  care  should  be  taken  that  its  germs  are  not  scattered. 

To  rub  the  sore  eyes  with  the  hands  is  sure  to  get 
germs  on  them.  If  before  washing  the  hands,  the 
patient  handles  books,  toys,  or  any  similar  thing,  some 
of  the  germs  are  likely  to  be  left  on  these  articles. 
Other  persons  using  these  things  get  germs  on  their 
hands.  If  then  one  such  rubs  his  own  eyes  with  un- 
washed hands,  the  circuit  from  the  diseased  eyes  to  well 
ones  will  be  completed  and  the  seed  planted  for  another 
case  of  eye  trouble.  One  can  hardly  expect  to  keep 
germs  from  getting  on  the  hands,  since  whatever  large 
numbers  of  people  handle,  such  as  door  knobs,  stair 
railings,  car  straps,  library  and  school  books,  are  likely 


244  THE   BODY  IN  HEALTH 

to  carry  them.  But  one  can  prevent  their  being  intro- 
duced into  the  eyes,  if  he  heeds  this  most  important 
rule  :  Never  rub  the  eyes  with  unwashed  hands. 

The  careful  provision  made  by  nature  to  protect  the 
eyes  from  dust  is  enough  to  point  out  to  us  the  fact  that 
dust  is  very  injurious  to  the  eyes.  It  irritates  the  lining 
of  the  eyelids,  scratches  the  surface  of  the  eye  and  may 
carry  into  it  the  germs  that  cause  inflammation.  If  a 
speck  of  dust,  a  cinder,  or  some  substance  gets  into  the 
eye,  do  not  rub  it,  as  this  may  cause  the  particle  to  be- 
come embedded  in  the  lining  or  in  the  surface  of  the  eye. 
Carefully  draw  the  upper  lid  over  the  lower.  In  many 
cases  this  will  remove  the  particle.  Or  holding  up  the 
eyelid  and  moving  the  eye  about  may  remove  it.  It 
may  sometimes  be  washed  out  by  bathing  the  eye. 

HEALTH  PROBLEMS 

1.  Can  you  give   any  estimate   of  the   number  of  pictures 
that  are  recorded  in  your  brain  ?     Do  you  think  all  the  objects 
you  have  ever  seen  have  left  images  in  your  brain  ?     Why  ? 

2.  What  do  you  think  is  the  reason  that  the  nose  has  been  made 
so  prominent,  while  the  eyes  have  been  set  back  in  sockets  ? 

3.  See  if  you  can  count  all  the  different  movements  that  can  be 
made  by  the  eye.     Is  each  movement  of  service  to  us  ?     How  ? 
How  are  we  able  to  execute  all  these  movements  ? 

4.  Make  a  drawing  which  will  show  what  a  concave  shape  is. 
One  that  will  show  a  convex  shape.     What  is  a  good  device  to 
distinguish  between  a  convex  and  a  concave  shape? 

5.  Suppose  one  should  lose  the  choroid  coat  of  the  eye.     What 
would  happen  to  his  sight  ? 

6.  Can  you  suggest  a  good  test  besides  the  one  mentioned  in  the 


GATEWAYS  OF  THE   MIND  — SIGHT        245 

text  to  show  that  an  image  lasts  after  the  object  from  which  it  is 
gained  is  removed  ?  Hold  the  pages  of  this  book  before  a  mirror. 
What  do  you  notice  regarding  inversion  and  reversal  of  images  ? 
Why  is  not  the  same  thing  true  of  our  features  when  we  look  at 
them  in  a  mirror  ? 

7.  How  near  can  you  put  a  small  object  to  the  eye  and  see  it  ? 
Why  can  not  you  see  it  when  it  is  brought  nearer?     Most  old 
people  wear  what  is  known  as  bifocal  lenses ;   that  is,  one  part  of 
the  lens  is  a  little  differently  shaped  from  the  other  part.     One 
part  is  used  for  reading  and  all  other  near  work,  another  part  for 
looking  at  objects  farther  away.     Why  do  not  young  people  have 
to  wear  glasses  like  this  ? 

8.  Why  is  the  lens  of  the  eye  thickened  when  one  looks  at  near 
objects?     Show  by  a  drawing. 

9.  Show  by  a  drawing  why  concave  lenses  are  worn  by  near- 
sighted people,  and  convex  lenses  by  far-sighted  people. 

10.  Suggest  an  experiment  which  will  illustrate  ways  in  which 
many  people  fatigue  their  eyes. 

11.  How  many  pupils  in  your  school  wear  glasses  ?  .  How  many 
of  them  have  had  their  eyes  tested  by  some  man  who  knew  just 
how  to  do  it  ? 

REVIEW  QUESTIONS 

1.  From  where   do  our  general   sensations  come?     Mention 
some  general  sensations. 

2.  Whence  come  our  special   sensations  ?     Mention   some   of 
them. 

3.  Why  is  it  proper  to  speak  of  the  senses  as  the  gateways  of 
the  mind  ? 

4.  Which  is  the  most  remarkable  of  the  gateways  of  the  mind  ? 

5.  How  do  impressions  get  from  the  back  of  the  eye  globe  to  the 
brain  ? 

6.  How  do  we  know  that  a  record  is  made  in  the  brain  when  we 
look  at  an  object  ? 


246  THE   BODY  IN  HEALTH 

7.  How  are  pictures  made  on  the  retina  ?     What  is  meant  by 
a  photograph's  being  bleached  on  the  retina  ? 

8.  How  do  the  eyelids,  eyelashes,  and  eyebrows  help  to  pro- 
tect the  eye  from  injury  ? 

9.  What  is  Nature's  provision  for  preventing  the  overflow  of 
tears  ?     How  are  the  tears  drained  away  ? 

10.  What  is  the  name  of  the  gland  in  which  the  tears  are  formed  ? 
Where  is  it  situated  ? 

11.  How  many  muscles  are  provided  for  each  eye?     How  are 
these  attached  to  the  eye  ? 

12.  What  is  the  outer  coat  of  the  eye  called?     The  middle 
coat  ?     The  inner  coat  ? 

13.  How  is  the  sclerotic  formed  ? 

14.  What  is  the  cornea  ?     Where  is  it  located,  and  what  is  its 
work  ? 

15.  Where  is  the  choroid  situated  ?     What  work  does  it  have 
to  do  ?     Where  is  the  iris,  and  what  is  its  work  ? 

1 6.  Where  is  the  pupil  of  the  eye  ? 

17.  Where  is  the  crystalline  lens,  and  what  is  its  office  in  the 
eye  ? 

1 8.  Where  is  the  vitreous  humor  ? 

19.  Where  is  the  aqueous  humor  ? 

20.  What  is  the  meaning  of  the  convex  lens  ? 

21.  Describe  the  toy  which  is  designed  to  show  that  an  image 
of  an  object  lasts  a  little  time  after  the  object  disappears. 

22.  Why  is  it  that  an  image  made  by  an  object  is  inverted  and 
the  sides  reversed  ? 

23.  What  happens  to  the  image  when  the  distance  of  an  object 
one  is  looking  at  is  changed  ? 

24.  What  happens  to  the  lens  when  the  amount  of  light  enter- 
ing the  eye  is  increased  or  decreased  ? 

25.  How  is  it  possible  for  the  lens  to  become  thicker  or  thinner  ? 

26.  What  sort  of  work  may  fatigue  the  muscles  controlling  the 
lens  ? 


GATEWAYS  OF  THE  MIND  — SIGHT        247 

27.  Why  is  it  that  some  people  have  short  sight  ?     Why  is  it 
that  some  people  have  far  or  long  sight? 

28.  What  kind  of  lens  must  a  near-sighted  person  wear  ?     What 
sort,  a  far-sighted  person  ? 

29.  With  what  do  we  really  see  objects  after  all  ? 

30.  Describe  the  care  that  should  be  taken  of  the  eyes  in  read- 
ing. 

31.  From  what  side  should  the  light  fall  upon  any  work  we  are 
doing  ? 

32.  What  troubles  are  likely  to  come  from  defective  eyesight  ? 

33.  What  care  should  be  taken  to  protect  the  eyes  from  dust 
and  the  like  ? 


CHAPTER   XIV 
GATEWAYS  OF  THE  MIND  —  HEARING 

EACH  special  sense  organ  gives  us  peculiar  sensations 
which  can  not  be  given  by  any  other  organ.  The  eye 
gives  sensations  of  light,  and  the  ear  sensations  of  sound. 
We  have  seen  that  sensations  are  caused  by  something 
in  the  world  about  us  acting  on  some  one  of  the  sense 
organs.  Now  a  little  experiment  will  help  to  make 
clear  to  us  what  it  is  that  gives  the  sensation  of  sound. 
Rest  one  end  of  a  board  upon  a  table,  holding  it  in 
position  with  the  left  hand.  Then  draw  a  pin  across 
the  board  with  the  right  hand,  and  you  will  notice  that 
the  board  trembles  or  vibrates.  If  you  now  press  the 
head  against  the  upper  end  of  the  board  and  draw  the 
pin  across  it  again,  a  loud  sound  will  be  heard.  The 
vibrations  of  the  board  will  be  communicated  through 
the  ear  to  the  nerves  of  hearing.  We  can  hear  the 
scratching  of  the  pin,  even  though  we  do  not  place  the 
ear  against  the  board,  because  the  vibrations  of  the 
board  start  vibrations  in  the  surrounding  air  and  these 
sound  waves  are  brought  to  the  ear.  When  the  string 
of  a  violin  or  harp  is  made  to  "sound,"  you  can  see  that 
it  is  in  rapid  vibration,  and  the  same  thing  takes  place 
in  all  sounding  bodies. 

24-8 


GATEWAYS  OF  THE  MIND  — HEARING      249 

You  can  get  some  idea  of  how  sound  travels  by  an- 
other simple  experiment.  Throw  a  stone,  into  the 
calm  water  of  a  pond.  You  will  see  that  a  little  ring 
of  waves  forms  itself  at  the  point  where  the  stone  struck 
the  water,  and  these  waves  travel  in  all  directions,  as 
far  as  the  water  extends.  If  a  piece  of  wood  is  made  to 
float  upon  the  water,  it  will  bob  up  and  down  as  the 
wave  reaches  it,  being  set  in  motion  by  the  movement 
that  was  started  in  the  water  by  the  stone.  Sound 
waves  are  made  in  the  air  by  the  vibration  of  sound- 
ing bodies  in  somewhat  the  same  way  as  the  waves  are 
made  in  the  water  by  the  falling  stone.  These  sound 
waves  traveling  through  the  air  reach  the  inner  ear 
and  set  its  movable  parts  in  motion,  as  the  wave  in  the 
water  sets  the  piece  of  wood  in  motion  when  it  reaches  it. 

We  see,  then,  that  sound  is  the  impression  produced 
on  us  when  the  vibrations  of  the  air  strike  on  the  drum 
of  the  ear.     When  the  vibrations  are  few,  the  HOW  we 
sound  is  deep  and  low ;    and  when  they  in-  hear- 
crease  in  number  it  becomes  shriller  and  higher.     The 
lowest  sound  that  can  be  heard  by  the  human  ear  is 
made  by  about  sixteen  vibrations  in  a  second.     When 
the  number  reaches  40,000  in  a  second,  the  sound  can 
not  be  heard  by  the  human  ear. 

Think  what  a  great  variety  of  air  movements  there 
must  be  in  order  to  cause  all  the  kinds  of  noises  we  hear 
and  the  musical  notes  covering  about  a  dozen  octaves. 
Yet  all  these  can  be  received  by  the  ear  and  sent  to  the 
brain;  and  each  keeps  its  own  peculiar  quality.  So 


250 


THE   BODY  IN  HEALTH 


sensitive  is  the  ear  that  we  can  at  once  recognize  a 
familiar  voice,  even  though  we  do  not  see  the  face  of  the 
speaker.  Let  us  take  a  look  inside  the  ear  and  examine 
the  wonderful  mechanism  by  which  this  is  done. 

(1)  What  is  called  the  outer  ear  is  (a)  the  part  that  we 
can  see,  and  that  we  commonly  speak  of  as  "  the  ear," 

and  (b)  the  auditory 

The  parts  ,  t         ,  f 

of  the  ear.  canal  or  tube  through 

which  the  vibrations 
pass  to  the  drum.  The  ear 
that  we  see  seems  to  be  placed 
where  it  is  for  the  purpose  of 
gathering  up  sound  waves. 
You  will  often  see  a  person 
who  is  a  little  deaf  placing 
the  hand  behind  the  ear,  and 
bringing  it  forward  to  assist 
the  hearing.  Ear  trumpets 
are  also  used  for  this  purpose. 
The  drum  is  a  membrane 
(the  tympanic  membrane) 
stretched  across  the  lower  end 
of  the  canal.  It  vibrates  like  the  head  of  a  drum  when 
the  sound  waves  strike  upon  it.  Glands  along  the 
canal  secrete  the  wax  which  guards  the  entrance  to  the 
drum. 

(2)  The  middle  ear,  or  drum  cavity,  is  connected 
with  the  throat  or  pharynx  by  a  small  canal  called  the 
eustachian  tube.     The  object  of  this  tube  is  to  allow  a 


THE  WONDERFUL  MECHANISM  OF 
THE  EAR. 

t,  external  auditory  canal;  2,  eus- 
tachian tube;  3,  middle  ear; 
4,  internal  ear;  5,  tympanic 
membrane;  6,  auditory  nerve; 
7,  pharynx. 


GATEWAYS  OF  THE  MIND  — HEARING      251 


change  of  air  in  the  drum  cavity  so  as  to  keep  it  at 
about  the  same  density  or  pressure  as  the  air  outside. 
Otherwise  the  tympanic  membrane  might  be  bulged 
inward  or  outward  by  the  unequal  pressure  on  its 
two  sides. 

The  air  in  the  ear  may  be  changed  in  the  following 
manner :    Grasp  the  nostrils  between  the  thumb  and 


The  Hammer 
(Malleus). 


The 

Shell  Tube 
(Cochlea). 


The  Anvil 
(Incus). 

ALL  THESE    DEVICES    ARE    NECESSARY    IN    ORDER  THAT   WE    MAY    GET    SENSATIONS 

OF    SOUND. 

finger,  take  a  full  breath  through  the  nose,  holding  it 
tightly  closed.  As  the  air  can  not  pass  out  through 
the  usual  channel,  the  nostrils,  it  is  forced  up  through 
the  eustachian  tube  to  the  middle  ear.  It  cannot  pass 
through  the  ear,  unless  the  drum  membrane  has  been 
torn.  When  an  opening  has  been  made  in  the  mem- 
brane, a  whistling  sound  may  be  heard  when  the  ears 


252  THE   BODY  IN  HEALTH 

are  inflated  in  this  way.  This  inflation  of  the  ears 
should  not  be  repeated  very  frequently,  but  it  may 
sometimes  give  relief  and  restore  the  hearing  when  the 
ears  are  "stuffed  up"  by  a  cold. 

Passing 'across  the  middle  ear,  from  its  outer  to  its 
inner  side,  is  a  chain  of  three  very  small  bones  (the 
hammer,  anvil,  and  stirrup).  These  bones  are  bound 
together  and  attached  to  the  walls  of  the  drum  cavity 
by  ligaments.  They  are  arranged  in  such  a  way  that 
when  the  drum  membrane  is  made  to  vibrate  by  sound 
waves,  the  motion  is  communicated  by  them  to  the 
cochlea.  The  cochlea  is  given  this  name  because  it  is 
shaped  just  like  a  snail  shell.  It  contains  a  great 
number  of  nerve  fibers  of  different  lengths  and  is 
thought  to  be  that  part  of  the  ear  which  distinguishes 
musical  notes. 

(3)  The  cochlea  is  situated  at  the  entrance  to  the 
inner  ear,  which  consists  of  small  bony  spaces  and  tubes 
called  the  bony  labyrinth,  within  which  is  a  mem- 
branous labyrinth.  The  membranous  labyrinth  is 
lined  with  very  sensitive  cells,  between  which  are  the 
endings  of  the  nerve  fibers  that  connect  the  ear  with  the 
brain. 

We  can  now  get  some  idea  of  what  takes  place  every 
time  we  hear  a  sound.  The  vibrations  or  sound  waves 
are  concentrated  by  the  outer  ear.  They  strike  upon 
the  drum,  and  are  communicated  from  it  to  the  chain 
of  small  bones  which  transmit  it  to  the  inner  ear,  where 
it  makes  an  impression  upon  the  sensitive  nerve  endings. 


GATEWAYS  OF  THE  MIND  — HEARING      253 

This  impression  is  transmitted  through  the  auditory 
nerve  to  the  brain,  producing  the  sensation  of  sound. 
The  ears  have  no  lids  or  natural  covering  by  means  of 
which  they  can  shut  out  sound  as  the  eyelids  shut  out 
light.  The  nerves  of  the  ear  remain  active  during 
sleep,  reporting  all  noises  to  the  brain.  The  sounds  to 


IN  TESTING  A  PERSON'S  HEARING  BE  CAREFUL  TO  HAVE  HIM  CLOSE  HIS 
EYES,  SO  THAT  HE  CANNOT  SEE  HOW  NEAR  OR  FAR  AWAY  THE 
WATCH  IS.  WHY  ? 

which  one  is  accustomed  do  not  prevent  sleep,  al- 
though impressions  brought  to  the  brain  through  the 
ear  are  often  curiously  woven  into  dreams.  Unusual 
sounds  generally  cause  awakening.  Why,  do  you 
think  f 


254  THE   BODY  IN  HEALTH 

An  examination  of  hundreds  of  children  in  Europe 
showed  that  one  quarter  of  them  were  a  little  deaf, 
The  care  many  of  them  without  knowing  anything 
of  the  ears,  about  it.  Children  are  sometimes  thought  to 
be  dull  and  inattentive  when  the  real  trouble  is  that 
they  do  not  hear  well  what  is  said  to  them. 


THIS    BOY    PROBABLY   HAS    A   DEFECT   IN    HEARING. 

It  is  a  good  thing  to  have  the  ears  tested  to  find  out  if 
the  hearing  is  perfect.  A  simple  test  which  you  can 
make  for  yourself  is  to  find  out  how  far  away  you  can 
hear  the  ticking  of  a  watch.  If  your  hearing  is  good, 
you  should  be  able  to  hear  the  watch  when  it  is  held  as 
much  as  fifty  inches  from  your  ear.  If  you  hear  very 
much  better  with  one  ear  than  with  the  other,  or  if  you 


GATEWAYS  OF  THE  MIND  —  HEARING      255 

can  not  hear  the  watch  tick  at  a  distance  of  more  than 
thirty  inches,  your  ears  should  be  examined. 

Sometimes  a  cold  will  cause  deafness  for  a  time. 
Catarrh  of  the  nasal  passages  or  of  the  throat  may 
spread  to  the  eustachian  tube  and  cause  serious  trouble. 
One  who  wishes  to  have  good  hearing  will  be  careful  not 
to  take  cold. 

Children  sometimes  shout  or  blow  into  each  other's 
ears  for  fun.  This  is  very  dangerous.  It  may  send 
such  a  strong  air  current  down  the  canal  as  to  rupture 
the  drum  membrane  and  cause  total  deafness.  A  blow 
on  the  ear  or  on  the  side  of  the  head  may  also  seriously 
injure  the  ear. 

The  drum  may  be  torn  and  the  hearing  injured  by 
using  a  sharp  instrument,  such  as  a  pin  or  a  toothpick, 
to  clean  out  the  ear.  The  wax  in  the  ear  is  placed  there 
by  nature  as  a  protection  and  should  be  left  undis- 
turbed. If  the  ears  are  carefully  washed  and  wiped 
out  every  day,  there  will  be  little  danger  that  it  will 
harden  and  cause  trouble. 

If  anything  accidentally  gets  into  the  ear,  do  not 
work  at  it.  Hold  the  head  over  to  one  side  while 
water  is  made  to  run  in  from  a  syringe.  If  an  insect 
gets  in  the  ear,  a  little  oil  will  either  kill  it  or  make  it 
come  out. 

HEALTH  PROBLEMS 

i.  How  do  blind  people  manage  to  get  around?  If  a  person 
were  born  blind,  do  you  think  he  would  have  any  images  ?  Why  ? 


256  THE   BODY  IN  HEALTH 

2.  How  do  deaf  people  manage  to  adapt  themselves  to  people 
and  things  around  them  ? 

3.  Why  is  it  not  possible  to  make  much  sound  with  a  drum 
unless  the  head  is  taut  ? 

4.  See  if  you  can  prove  that  the  head  of  the  drum  vibrates  when 
it  is  struck.     See  also  if  you  can  prove  that  a  tuning  fork  vibrates 
when  it  is  giving  forth  sound. 

5.  Show  whether  the  receiver  of  the  telephone  is  like  the  drum 
of  the  ear  in  any  respect. 

6.  Is  "  ear  drum  "  a  good  term  to  apply  to  the  membrane  in 
the  ear  upon  which  sound  waves  strike  ?     Why  ? 

7.  Try  to  imagine  what  goes  on  in  the  ear  when  one  is  walking 
along  a  very  noisy  city  street.     Do  you  think  this  is  good  for  the 
ear?     Why? 

8.  It  is  said  that  sometimes  a  cannon  bursts  the  ear  drum  of 
the  gunner.     Explain. 

9.  Suppose  the  outer  ear  should  be  lost.     What  would  be  the 
effect  upon  the  hearing  ? 

10.  Suppose  you  go  from  some  level  plain  to  the  top  of  a  high 
mountain.     Which  way  will  the  ear  drum  bulge  ?     Why  ? 

11.  When  people  in  crossing  the  mountains  have  trouble  with 
their  ears,  physicians  always  try  to  open  up  the  eustachian  tube. 
Why? 

12.  Why  can    one    usually  sleep  soundly  when    the  wind  is 
blowing  moderately  or  when  his  bedroom  is  near  a  lake  or  river, 
and  the  water  is  lapping  on  the  shore  ? 

13.  Why  is  a  sleeping  person  usually  awakened  when  people 
come  into  his  room,  though  he  may  not  be  awakened  when  there 
is  a  great  deal  of  noise  made  outside  ? 

REVIEW  QUESTIONS 

I.   Which  organ  gives  the  sensation  of  light  ?    Which  one  gives 
the  sensation  of  sound  ? 


GATEWAYS  OF  THE  MIND —  HEARING      257 

2.  How  are  sensations  caused  ? 

3.  Describe  the  experiment  which  was  made  to  show  what  it  is 
that  gives  sensation  of  sound. 

4.  What  is  meant  by  vibrations  in  the  atmosphere  ?     What  is 
meant  by  sound  waves  ? 

5.  How  can  one  illustrate  the  traveling  of  sound   waves  by 
throwing  a  stone  in  the  calm  water  of  a  pond  ? 

6.  How  do  the  sound  waves  in  the  air  give  a  sensation  of  sound  ? 
What  is  meant  by  the  ear  drum  ? 

7.  Why  is  it  that  some  sounds  are  higher  than  others  ? 

8.  What  is  the  smallest  number  of  vibrations  a  second  that  the 
ear  can  hear  ?     What  is  the  largest  number  ? 

9.  How  is  it  possible  that  we  can  recognize  the  voice  of  a  famil- 
iar friend  ? 

10.  What  is  meant  by  the  outer  ear  ? 

11.  Where  is  the  auditory  canal  ? 

12.  What  is  meant  by  the  middle  ear? 

13.  Where  is  the   eustachian  tube?     How  does  it  assist   the 
hearing  ? 

14.  What  is  likely  to  happen  when  the  eustachian  tube  gets 
blocked  up  ? 

15.  How  can  the  density  of  the  air  in  the  ear  be  changed  volun- 
tarily ? 

16.  Describe  the  three  small  bones  in  the  middle  ear. 

17.  What  is  the  cochlea  ?     Why  is  it  given  this  name  ? 

1 8.  What  is  the  bony  labyrinth  ? 

19.  What  is  the  membranous  labyrinth  ? 

20.  Just  what  takes  place  in  the  ear  when  we  hear  a  sound  ? 

21.  Is  there  anything  in  the  ear  corresponding  to  the  eyelid 
which  covers  the  eye  ? 

22.  Can  one  shut  out  noises  during  sleep  ? 

23.  What  kind  of  noises  are  likely  to  keep  qne  awake  ? 

24.  How  many  of  the  children  examined  in  Europe  were  found 
to  be  deaf? 


258  THE   BODY  IN  HEALTH 

25.  What  is  the  effect  of  deafness  upon  one's  mind  ? 

26.  How  can  one  test  his  hearing  to  find  out  whether  it  is  nor- 
mal ? 

27.  Why  will  a  cold  sometimes  cause  deafness  ?     It  is  said  that 
catarrh  often  causes  deafness.     How  is  this  possible  ? 

28.  Should  children  shout  in  the  ears  of  one  another  ?     Why  ? 

29.  What  may  be  the  effect  upon  the  ear  drum  of  a  blow  on  the 
ear  ?     What  is  the  danger  of  using  a  tooth  pick  or  a  pin  in  the  ear  ? 

30.  What  is  the  purpose  of  the  wax  in  the  ear  ?     How  should  it 
be  removed  when  necessary  ? 


CHAPTER  XV 
GATEWAYS  OF  THE  MIND, — TOUCH,  TASTE,  AND  SMELL 

PERHAPS  you  know  that  the  sense  of  smell  does  not 
play  nearly  so  important  a  part  in  the  life  of  human 
beings  as  it  does  in  the  life  of  some  of  the  lower  animals. 
Do  you  think  it  may  be  that  it  has  been  largely  lost  in 
man  through  neglect  of  use  ?  In  a  dog  this  sense  is  so 
acute  that  it  seems  to  be  of  more  service  often  than  the 
sense  of  sight. 

The  olfactory  nerves,  or  nerves  of  smell,  end  in  the 
mucous  membrane  of  the  upper  part 
of  the  nasal  cavity.  Here  are  situ- 
ated delicate  cells  very  sensitive  to 
odors.  These  are  the  only  nerve  cells 
in  the  body  exposed  to  the  outside 
world.  From  the  olfactory  cells  in 
the  nose  nerve  fibers  pass  to  the  brain. 

r™  r  „     .  !  !         THIS  ILLUSTRATION  SHOWS 

Ine  sense  or  smell  is  excited  only  THE  OLFACTORY  NERVE 
by  very  small  particles  of  certain  ENDINGS  IN  THE  MUCOUS 
substances  brought  to  these  sensitive  MEMBRANE  OF  THE 

H        V  •  .  ^r>1    .          .  NASAL    CAVITY. 

cells    by   moving  air.     This  is  why 

we  "sniff"  the  air  when  we  wish  to  smell  anything. 

When  substances  having  an  odor  are  held  in  the 
iriputh,  the  particles  that  give  the  sensation  of  odor 

259 


z6o 


THE   BODY  IN  HEALTH 


are  carried  through  the  nose  by  the  outgoing  breath. 

Those  sensations  of  smell  we  often  confuse  with  taste. 

Confusing    We  frequently  think  we  taste  something  which 

smell  and    in  reality  we  only  smell.      Try  holding  the 
nose  so  that  the  breath  cannot  escape  through 

it,  while  a  piece  of  onion  is  held  on  the  tongue.  You 
will  then  not  notice  any  of  the  flavor  of 
the  onion.  When  the  nose  is  obstructed 
by  a  cold  the  sense  of  smell  is  .greatly 
lessened  or  even  lost  for  a  time.  At 
such  times  the  most  highly  flavored  sub- 
stances seem  to  have  no  taste. 

Neglected  colds,  which  result  in 
chronic  catarrh  of  the  nasal  passages, 
Destroying  maY  'ead  to  entire  loss  of  smell. 

THE  OLFACTORY  MU-  the  sense     The    mucous    membrane    may 

COUS      MEMBRANE.     of  qmo11  v  1-1  1  1  1 

NOTICE  HOW  THE  become  thickened,  so  that  the 

NERVE  ENDINGS  odorous  particles  carried  by  the  air  can 
not  come  in  contact  with  the  nerves  of 
smell.  The  use  of  snuff  and  cigarette 
smoking  are  also  likely  to  be  destructive  to  this  useful 
sense.  Tobacco  smoke  has  a  paralyzing  effect  upon 
the  nerves,  besides  inflaming  the  mucous  membrane. 
The  brain  receives  valuable  information  through 
the  sense  of  smell,  as  well  as  the  pleasurable  sensations 
caused  by  delightful  odors.  It  helps  us  in  determining 
whether  articles  are  fit  for  food.  Food  that  is  beginning 
to  spoil  usually  gives  forth  an  unpleasant  odor.  The 
sense  of  smell  also  warns  us  of  the  presence  of  poisonous 


ARE      EXPOSED     TO 
THE    AIR. 


TOUCH,  TASTE,  AND  SMELL 


261 


gases  in  the  air.  It  is  a  signal  placed  at  the  entrance 
of  the  body,  and  its  warnings  should  be  promptly 
heeded.  When  neglected,  it  soon  ceases  to  give  warn- 
ing of  the  presence  of  danger.  This  is  shown  by  the 
sensation  experienced  on  entering  an  unventilated 
bedroom,  or  a  crowded  room,  after  a  walk  out-of-doors. 
One  is  surprised  that  the  persons  in  the  room  can  en- 
dure the  unpleasant  odor  which  he  at  once  recognizes. 
But  if  he  remain  in  the  room  for 
some  time,  he  soon  becomes  as 
unconscious  of  it  as  the  others. 

Examine  your  tongue,  and 
you  will  find  on  its  upper  sur- 
face many  little  promi-  _ 

u-  u  11  j  The  sense 

nences  which  are  called  Of  taste,  a 

papillae.       If    you     look   sentinel  of 
I        ,  ,  .n   the  body. 

closely  enough,  you  will 
notice  some  large   papillae   that 
project  quite  prominently  above 
the    others.     These    large   ones 
are  called  the   papillae   circum- 

II  I  !  .  1*1  THE    TONGUE. 

vallate,  because  there  is  a  little     I>K          2>pointoftongue. 


NOTICE   THE    PAPILLJE    ON 


3,  papillae;  4,  base;    5,  epi- 
glottis ;  6,  orifice  of  pharynx. 


valley    or    furrow    surrounding 

each  one.     The  purpose  of  this 

little  trough  is  to  receive  the  fluids  of  the  mouth  in  which 

are  dissolved  the  savory  substances  of  the  food.     In  the 

trough  are  the  taste  buds,  each  one  of  which  is  the 

expanded  end  of  a  bunch  of  nerves.     These  taste  buds 

are  made  up  of  thousands  of  delicate  nerve  filaments 


262  THE   BODY  IN  HEALTH 

which  by  means  of  their  arrangement  are  brought 
into  direct  contact  with  the  liquids  containing  the 
flavors  of  the  food.  If  these  sensitive,  jellylike  masses 
were  right  on  the  surface  of  the  tongue,  they  would 
soon  be  injured.  They  are  protected  by  being  hidden 
away  down  in  this  little  groove. 

The  flavor  of  many  substances  that  we  think  we  taste 
is  really  due  to  their  odor,  as  we  noticed  above.  There 
are  only  four  true  taste  sensations :  sweet,  sour,  salt, 
and  bitter.  It  has  been  shown  that  each  of  these 
flavors  is  recognized  by  a  special  set  of  nerves.  Bitter 
is  most  distinctly  recognized  at  the  back  of  the  tongue, 
and  the  other  flavors  at  the  tip  and  sides. 

Should  you  expect  that  condiments,  such  as  mustard 
and  pepper,  and  all  substances  which  burn  the  tongue, 
would  injure  the  nerves  of  taste  and  lessen  their  ability 
to  recognize  flavors  ?  Why  ?  Should  you  expect  that 
alcohol  would  paralyze  the  nerves  of  taste  ?  Why  ? 
A  teaspoonful  of  alcohol  held  in  the  mouth  for  a  few 
minutes  will  so  benumb  the  nerves  that  ordinary 
flavors  cannot  be  detected.  The  habitual  use  of 
alcohol  permanently  injures  this  valuable  sense. 

The  sense  of  taste  is  given  to  us  not  merely  as  a 
means  of  pleasure  but  as  a  guide  to  our  appetites. 
It  is  one  of  the  body's  most  important  safeguards. 
We  have  the  old  proverb,  ""Hunger  is  the  best  sauce," 
because  when  one  is  hungry  almost  any  sort  of  whole- 
some food  may  be  eaten  with  relish.  When  the  sense 
of  hunger  is  satisfied  the  food  no  longer  tastes  good. 


TOUCH,  TASTE,  AND   SMELL  263 

A  natural  taste  is  a  sentinel  which  promptly  gives 
notice  to  the  eater  when  he  has  taken  enough  of  any 
sort  of  food  to  satisfy  his  present  needs. 

Another   important    avenue   to   the   mind,    through 
which  a  great  amount  of  valuable  information  comes 
to    us,    is    the    sense    of   touch.     The    nerve  The  sense 
endings  of  this  sense  are  in  the  skin.     When  of  touch, 
these  nerves  are  most  abundant,  the  sense  of  touch 
is  most  acute,  —  in  the  ends  of  the  fingers,  the   lips, 
and  the  tip  of  the  tongue.     When  we  touch  anything, 
the  outer  skin  or  epidermis  is  pressed  upon  these  nerve 
endings,  and  an  impulse  is  started  to  the  brain,  causing 
a  sensation  of  feeling. 

The  mind  is  able  to  judge  of  many  things  through 
the  sense  of  touch.  By  its  aid  we  are  able  to  distinguish 
the  forms  of  objects,  whether  they  are  smooth  or  rough, 
hard  or  soft,  rigid  or  elastic.  A  little  baby,  reaching 
out  with  its  hands  to  take  hold  of  everything  it  sees, 
is  making  an  unconscious  effort  to  inform  its  mind  and 
develop  its  judgment  by  means  of  this  sense. 

The  delicacy  of  the  sense  of  touch  may  be  greatly 
increased  by  cultivating  it.  In  the  blind,  in  whom  it 
has  to  take  the  place  of  the  sense  of  sight,  it  is'  very 
acute. 

The  practice  of  training  the  sense  of  touch  alone  is 
shown  in  the  case  of  Helen  Keller,  who  lost  both  sight 
and  hearing  before  she  was  two  years  old.  From  that 
time  the  only  avenue  to  her  mind  (with  the  exception 
of  taste  and  smell)  was  the  sense  of  touch.  Yet  she 


264 


THE  BODY  IN  HEALTH 


The  sense 
of  tem- 
perature. 


has  passed  successfully  through  all  the  stages  of  an 
ordinary  college  education  and  has  become  better 
informed  than  most  persons  having  the  use  of  all  their 

senses.  It  has  often  been 
said  of  her  that  she  "sees 
more  with  her  fingers 
than  other  persons  with 
their  eyes." 

Besides  the  nerves  that 
are  stimulated  by  touch, 
there  are  others 
in  the  skin  that 
are     stimulated 
by  heat   and    others   by 
cold.     It  is  a  curious  fact 
that  warmth  and  cold  are 
not  felt  on  the  same  spot 
of  skin.     The  hot  spots 
and    cold    spots    are    ar- 
ranged in  curved  lines  or 
chains,  starting  from  the  hair  roots. 

The  effect  that  may  be  produced  upon  the  body  by 
mearis  of  temperature,  acting  through  the  nerves  that 
carry  to  the  brain  the  sensations  of  heat  and  cold,  has 
already  been  studied.  We  have  seen  that  by  the  stimu- 
lation of  these  nerves,  impulses  may  be  carried  to  every 
organ  and  tissue,  increasing  the  blood  circulation  and 
exciting  every  kind  of  bodily  activity. 
A  daily  cold  bath  is  a  training  of  the  nerves  and  the 


THE    SENSE    OF   TOUCH    IN   THE    BLIND 
IS    VERY   ACUTE. 


TOUCH,   TASTE,  AND  SMELL  265 

brain,  as  well  as  of  the  skin  and  its  vessels.  The  im- 
pression made  by  the  contact  of  the  cold  water  with  the 
skin  sends  a  thrill  from  the  surface  to  the  center,  reach- 
ing every  nook  and  corner  and  stirring  every  cell  and 
fiber  of  the  body.  By  this  means  the  whole  body  is 
aroused  and  energized. 

Another  sensation  with  which  we  are  all  familiar  is 
pain.     It  is  not  known  whether  this  sensation  has  its 
own  special  sets  of  nerves,  but  it  is  thought  The  use 
that  it  is  caused  by  too  great  stimulation  of  ofpa"1- 
any  of  the  nerves  of  feeling.     Although    unpleasant 
and  hard  to  bear,  pain  is  one  of  the  most  useful  sensa- 
tions that  we  experience.     It  is  a  danger  signal,  calling 
our  attention  to  the  fact  that  something  is  wrong  and 
needing  attention. 

Pain  is  often  a  means  of  preserving  the  body  from 
serious  injury.  For  example,  if  it  were  not  for  the 
pain  caused  a  little  child  with  no  experience  by  burning, 
the  child  might  keep  its  hand  in  the  fire  until  it  was 
destroyed.  Toothache  is  a  warning  that  a  tooth  is 
beginning  to  decay,  a  fact  that  otherwise  might  not 
be  discovered  in  time  to  save  the  tooth. 

People  often  try  to  stop  or  kill  pain  by  drugs  or  other 
means,  but  pay  no  attention  to  the  trouble  of  which 
the  pain  is  giving  them  notice.  This  is  as  foolish  as 
it  would  be  to  kill  a  sentinel  because  he  gave  us  warn- 
ing of  an  approaching  danger,  while  we  made  no  effort 
to  avert  the  danger. 

The  purpose  of  a  sensation  of  pain  is  to  tell  us  that 


266  THE   BODY  IN  HEALTH 

there  is  something  wrong  with  the  body  or  with  our 
way  of  treating  it.  The  thing  to  do  is  not  to  take  some 
kind  of  "pain  killer"  but  to  find  out  what  is  causing 
the  pain  and  try  as  far  as  possible  to  have  it  remedied. 
This  can  often  be  done  only  by  consulting  a  reliable 
physician. 

HEALTH  PROBLEMS 

1.  How  does  an  animal  like  the  dog  use  the  sense  of  smell? 
Suppose  the  animal  should  lose  this  sense,  could  it  get  along  without 
it?     Why? 

2.  Do  you  think  the  horse  makes  use  of  the  sense  of  sight  more 
than  the  sense  of  smell  ?     Give  reasons  for  your  answer. 

3.  We  say  that  animals  "  prick  up  their  ears  "  when  their  atten- 
tion is  attracted  by  any  noise.     Do  they  do  anything  resembling 
this  when  their  attention  is  attracted  by  odors  ? 

4.  A  lion  when  he  is  stealing  upon  prey,  or  a  hunter  when  he  is 
tracking  an  animal,  approaches  from  the  opposite  direction  from 
which  the  wind  is  coming.     Why  does  he  do  this  ? 

5.  Suggest  two  or  three  good  tests  to  show  how  the  sense  of 
smell  helps  the  sense  of  taste.     Does  food  with  a  disagreeable  smell 
ever  have  a  good  taste  ?     If  you  think  so,  give  an  example. 

6.  Why  has  Nature  arranged  it  so  that  taste  and  smell  work 
together  so  closely  ? 

7.  Why  has  Nature  arranged  it  so  that  some  odors  are  very 
pleasant  while  others  are  very  disagreeable  ? 

8.  Try  a  bitter  tasting  object  on  the  tip  of  your  tongue  to  see 
if  you  can  detect  it. 

9.  Put  something  sour  as  far  back  on  the  tongue  as  possible  to 
see  if  you  can  taste  it.     Explain. 

10.  You  might  try  the  experiment  of  putting  pepper  on  some 
article  of  food  so  that  it  will  burn  the  tongue,  then  see  if  you  can 


TOUCH,  TASTE,  AND  SMELL  267 

get  the  taste  of  bread  or  any  other  article,  as  well  as  you  could 
before  you  took  the  pepper. 

11.  Why  did  Nature  arrange  it  so  that  an  article  of  food  would 
lose  its  taste  when  enough  of  it  was  eaten  ? 

12.  When  the  epidermis  is  rubbed  off  in  an  accident,  why  is 
the  exposed  part  so  painful  to  the  sense  of  touch  ? 

13.  Why  has  Nature  made  the  sense  of  touch  so  acute  in  the 
tips  of  the  fingers,  in  the  lips,  and  so  on  ? 

14.  In  what  parts  of  the  skin  is  the  sense  of  touch  very  dull  ? 
Explain. 

15.  Can  you  think  of  any  way  to  show  that  cold,  heat,  and 
touch  are  not  recognized  on  the  same  spot  on  the  skin  ? 

1 6.  Why  does  cold  air  usually  give  one  a  good  appetite  ? 

17.  Mention  some  useful  pains.     Why  should  they  be  useful? 
Should  we  try  to  avoid  them  ?     Why  ?     How  can  we  do  so  ? 

REVIEW  QUESTIONS 

1.  How  is  it  possible  for  odors  to  make  an  impression  on  the 
brain  ? 

2.  What  is  the  meaning  of  olfactory  ?    What  are  the  olfactory 
cells  ?     The  olfactory  nerves  ? 

3.  How  is  the  sense  of  smell  excited  ? 

4.  Why  do  people  "  sniff  the  air "  when  they  want  to  smell 
anything  ? 

5.  When  one  has  a  cold  or  catarrh,  why  do  pleasant  tasting 
things  often  lose  their  taste  ? 

6.  What  is  likely  to  be  the  effect  of  cigarette  smoking  and  snuff 
taking  upon  the  sense  of  smell  ? 

7.  Can  the  sense  of  smell  become  accustomed  to  disagreeable 
odors  so  that  one  cannot  detect  them  ?     Give  illustrations. 

8.  If  you  examine  the  surface  of  the  tongue,  what  do  you  find 
there  ? 

9.  How  has  Nature  arranged  it  so  that  we  can  taste  things  ? 


268  THE   BODY  IN  HEALTH 

10.  Where  are  the  taste  buds  ?     Of  what  use  to  us  are  they? 

11.  Suppose  the  taste  buds  were  on  the  surface  of  the  tongue, 
what  might  happen  to  them  ? 

12.  What  are  the  true  taste  sensations  ? 

13.  On  what  part  of  the  tongue  is  sour  recognized?     Where 
are  the  other  flavors  recognized  ? 

14.  What  is  the  effect  of  condiments  such  as   mustard   and 
pepper  on  the  sense  of  taste  ? 

15.  What  is  the  effect  of  alcohol  on  the  sense  of  taste  ? 

16.  Why  is  the  natural  taste  a  sentinel  ? 

17.  Where  are  the  nerve  endings  for  the  sense  of  touch  ? 

1 8.  Where  is  the  sense  of  touch  most  delicate  ? 

19.  What  can  the  mind  find  out  about  objects  through  the 
sense  of  touch  ? 

20.  What  is  meant  by  the  "sense  of  temperature"  ? 

21.  What  effect  may  be  produced  on  the  body  by  cold  ? 

22.  Why  will  a  cold  bath  stir  up  every  part  of  the  body  ? 

23.  What  is  meant  by  the  sensation  of  pain  ? 

24.  Are  pain  sensations  useful  to  the  body  ?     Explain. 

25.  Is  it  advisable  to  try  to  kill  pain  by  the  use  of  drugs  ? 
Why? 


CHAPTER   XVI 
THE  BODY'S  ENEMIES  —  ALCOHOL  AND  TOBACCO 

THE  first  thing  to  do  for  any  one  who  wants  good 
health  is  to  guard  against  the  enemies  of  the  body. 
We  have  already  learned  about  some  of  these  enemies ; 
but  we  must  give  special  attention  in  this  chapter  to 
certain  enemies,  because  of  the  great  harm  they  will 
do  the  body  unless  we  can  avoid  them. 

There  are  certain  poisonous  substances,  very  harm- 
ful to  the  body,  which  are  yet  capable  of  giving  rise 
for  the  moment  to  pleasurable  sensations.  They  give 
one  a  feeling  of  happiness,  wellbeing,  or  comfort. 
For  this  reason,  they  have  come  to  be  largely  used 
by  human  beings,  in  spite  of  their  poisonous  character. 
Among  those  chiefly  used  in  this  country  are  alcohol 
and  tobacco. 

Alcohol  comes  of  a  bad  family.  It  is  closely  allied 
to  naphtha,  benzine,  and  kerosene,  which  no  one 
would  think  of  drinking.  In  a  pure  state,  alcohol 
destroys  instantly  all  living  tissues  with  which  it 
comes  in  contact.  It  is  seldom  found  pure,  usually 
containing  from  two  to  fifty  per  cent  of  water. 

If  a  plant  be  watered  with  diluted  alcohol,  its  leaves 

269 


270  THE   BODY  IN   HEALTH 

will  soon  wither,  turn  yellow,  and  the  plant  will  die. 
Alcohol  ^  tadpole  dropped  into  a  vessel  containing 
kills  alcohol  will  die  in  a  minute.  Alcohol,  taken 

living          even  jn  small  doses,  has  an  injurious    effect 

things.  IT-  •  riii  A 

upon  the  living  tissues  or  the  body.  A 
curious  accident  which  happened  to  a  hunter  many 
years  ago  made  it  possible  to  find  out  the  exact  effect 
which  alcohol  has  upon  the  stomach.  A  Canadian 
trapper  and  hunter,  named  Alexis  St.  Martin,  was 
shot  in  the  stomach.  The  wound  was  so  large  that 
the  flesh  did  not  close  up  and  heal  the  wound  in  the 
usual  way.  It  healed  only  the  edges,  leaving  a  hole 
two  and  one  half  inches  around.  A  piece  of  lining  of 
the  stomach  hung  down  and  formed  a  kind  of  curtain 
over  the  opening.  This  could  be  pushed  back  so  that 
one  could  look  in  and  see  what  went  on  in  the  stomach, 
just  as  Professor  Pawlow  was  able  to  look  into  the 
stomachs  of  his  dogs. 

Dr.  Beaumont,  a  physician  in  the  United  States  Army, 
invited  this  man  with  a  window  in  his  stomach  to  come 
and  live  with  him.  He  wanted  to  be  able  to  look  in 
whenever  he  pleased,  and  see  just  how  the  stomach 
acted  under  different  conditions.  Among  other  things, 
he  wanted  to  find  out  if  alcohol  was  helpful  to  the 
stomach  in  its  work  or  if  it  hindered  it  and  injured  it. 

Dr.  Beaumont  noticed  that  when  Alexis  was  given 
good  food  with  no  alcohol,  the  stomach  lining  was  of  a 
pink  color,  and  the  gastric  juice  was  thin  and  colorless. 
Then  he  tried  giving  him  a  certain  amount  of  alcohol 


THE   BODY'S   ENEMIES  271 

every  day.  He  then  noticed  that  the  lining  became 
of  a  red  color,  because  it  was  irritated  and  inflamed 
by  alcohol.  After  a  while,  small  sores  or  ulcers  formed 
on  it.  He  removed  some  of  the  gastric  juice  with  a 
tube  and  found  that  it  contained  a  thick  mucus  and 
sometimes  blood  from  the  sore  places.  He  then 
stopped  giving  him  alcohol  and  the  stomach  gradually 
healed  and  returned  to  its  natural  pink  color.  By 
this  Dr.  Beaumont  knew  that  the  continued  use  of 
alcohol  causes  disease  of  the  stomach. 


A    HEALTHY    STOMACH.  THE    STOMACH    OF    A    DRUNKARD 

IS  INFLAMED  AND  ULCERATED. 

Alcohol  does  more  than  simply  irritate  and  inflame 
the  stomach.     It  is  able  to  paralyze  the  nerves  so  that 
they  will  lose  their  sensibility.     On  one  oc-  some  of 
casion,    when   Alexis    St.    Martin    had    been  the  effects 
drinking  heavily  for  several  days,  Dr.  Beau-  °  0^^ 
mont    noticed   that    his   stomach   was   much  human 
inflamed   and   ulcerated,   but   Alexis   himself  body- 
knew  nothing  about  this.     He  felt  no  pain  or  discomfort 
in  his  stomach  but  only  complained  of  a  severe  head- 
ache. 

The  liver,  as  well  as  the  stomach,  is  injured  by  the 


272  THE   BODY  IN  HEALTH 

use  of  alcohol.  In  one  who  indulges  in  alcohol  for 
years,  it  becomes  shrunken,  hard,  and  almost  useless. 
The  outside  becomes  covered  with  little  knobs  so  that 
it  looks  like  the  sole  of  an  English  cartman's  shoe. 
For  this  reason  it  has  been  given  the  name  of  "hob- 
nailed liver. " 

Alcohol  has  the  effect  of  hardening  the  tissues. 
The  brain  in  a  healthy  state  is  so  soft  that  it  would 
not  retain  its  exact  form  if  it  were  not  supported  by 
the  skull.  The  sharpest  knife  is  required  to  cut  it 
without  tearing  it.  If  a  careful  examination  of  a  brain 
is  to  be  made,  it  is  necessary  to  put  it  in  alcohol  for 
weeks  or  months  in  order  to  harden  it.  But  the  brain 
of  a  drunkard  is  already  more  or  less  hardened.  An 
anatomist  declared  that  he  could  tell  the  drunkard's 
brain  in  the  dark  by  the  sense  of  touch  alone. 

Experiments  upon  living  animals  have  shown  the 
changes  that  take  place  in  the  nerve  cells  when  alcohol 
is  introduced  into  the  circulation.  Some  of  them 
almost  immediately  become  shriveled,  misshapen,  and 
incapable  of  performing  their  duty.  The  delicate 
branches  by  which  the  cells  come  in  contact  with  each 
other  are  drawn  back.  The  contact  of  the  cells  is 
thus  interrupted,  and  this  interferes  with  memory, 
reason,  and  judgment.  This  explains,  as  we  have 
seen,  the  mental  disturbances  which  take  place  in 
one  who  drinks  freely  of  alcoholic  beverages. 

When  an  animal  experimented  upon  with  alcohol 
recovers  from  an  intoxicating  dose,  the  nerve  cells 


THE   BODY'S  ENEMIES  273 

regain  their  natural  appearance.  But  when  the  use 
of  alcohol  is  habitual  and  long-continued,  some  of  the 
cells  become  permanently  injured.  Then  the  brain, 
mind,  and  character  are  permanently  changed. 

A  man  who  is  intoxicated  is  for  the  time  insane. 
When  the  intoxication  is  frequently  repeated,  this 
condition  of  mind  may  become  permanent,  making 
him  a  fit  subject  for  an  insane  asylum.  It  has  been 
shown  that  from  25  to  50  per  cent-  of  the  people  in  the 
insane  asylums  of  this  country  and  England  were 
brought  there  by  alcohol. 

Life  insurance  companies  know  that  one  who  uses 
alcohol  is  not  a  "good  risk."  He  is  not  likely  to  live 
so  long  as  one  who  does  not.  Statistics  based  on  their 
tables  show  that  for  every  temperate  person  who  dies 
between  the  ages  of  twenty-one  and  thirty,  fifty-one 
intemperate  persons  die.  In  other  words,  for  persons 
of  this  age,  the  mortality  of  liquor  users  is  five  hundred 
per  cent  greater  than  abstainers.  It  has  also  been 
shown  that  at  twenty  years  of  age,  a  temperate  man 
has  an  average  chance  of  living  for  forty-four  and  one 
fifth  years,  while  the  drinking  man  has  the  prospect 
of  only  fifteen  and  one  half  years. 

The  effects  of  alcohol  are  often  seen  even  more  plainly 
in  the  children  of  those  who  use  it  than  they  are  in 
themselves.  Dr.  Hodge,  Professor  of  Physiology  in 
Clark  University,  was  asked  to  make  some  experiments 
with  animals  to  find  out  some  of  the  effects  of  alcohol. 
In  some  of  his  experiments  he  used  four  dogs.  Two 


274  THE   BODY   IN  HEALTH 

of  these  were  given  alcohol  every  day  with  their  food, 
and  for  this  reason  he  called  them  Bum  and  Tipsy. 
The  other  two  were  Nig  and  Topsy.  During  the  four 
years  that  they  were  all  under  Dr.  Hodge's  care, 
Bum  and  Tipsy  had  twenty-three  puppies.  Some  of 
these  were  dead  when  they  were  born  and  many  of 
them  were  deformed.  Only  four  lived  to  grow  up. 
During  the  same  time  Nig  and  Topsy  had  forty-five 
puppies,  all  of  which  were  born  alive.  Only  four  were 
a  little  deformed,  and  forty-one  lived  to  grow  up. 

A  French  physician,  Dr.  Legraini  made  some  in- 
vestigations to  find  out  what  effect  it  had  upon  the 
children  when  the  parents  used  alcohol  freely.  This 
is  what  he  found:  "In  the  first  generation  from  in- 
ebriety the  mental  and  physical  degenerates  were 
77  per  cent  of  all ;  in  the  second  generation,  96  per 
cent  were  defectives ;  in  the  third  generation  not 
one  escaped ;  all  were  idiots,  insane,  hysterical,  or 
epileptic." 

All  these  things  show  us  that  alcohol  is  a  deceiver ; 
it  only  increases  all  the  miseries  that  it  promises  to 
Alcohol  a  relieve.  It  relieves  hunger,  because  it  takes 
deceiver,  away  the  appetite  and  the  power  to  digest 
food ;  but  it  does  not  nourish  the  body.  It  soothes 
pain  by  paralyzing  the  nerves,  but  it  does  not  remove 
the  cause  of  the  pain.  If  a  man  is  cold,  it  gives  him 
the  sensation  of  warmth,  but  he  is  actually  colder 
than  before.  It  makes  the  weak  man  feel  strong,  but 
he  is  actually  weaker  than  before.  It  causes  the  nerv- 


THE   BODY'S   ENEMIES  275 

ous  system  to  lie  and  to  make  a  man  think  he  is  happy, 
while  he  is  all  the  time  becoming  more  wretched. 

In  1862  the  attention  of  the  French  Emperor  was 
called  to  the  fact  that  the  number  of  lunatics,  paralytics, 
and  epileptics  in  the  hospitals  of  France  was  Tobacco  a 
five  times  as  great  in  proportion  to  the  popu-  cause  of 
lation  as  it  was  thirty  years  before.     There  disease- 
was  also,  it  was  noticed,   about  five  times  as  much 
tobacco  being  used   as  thirty  years   before.     It  was 
thought  that  there  might  be  some  connection  between 
these  two  things,  and  the  Emperor  appointed  a  com- 
mittee of  scientific  men  to  make  an  investigation. 

In  the  course  of  this  investigation,  the  students  in 
the  government  training  schools  were  divided  into 
two  classes  —  smokers  and  non-smokers.  The  physical 
condition  of  each  class  was  carefully  noted,  as  well  as 
the  amount  of  work  they  were  able  to  do.  It  was 
found  that  the  non-smokers  were  much  superior, 
physically,  mentally,  and  morally  to  the  smokers. 
A  law  was  at  once  passed  forbidding  the  students  in 
the  government  training  schools  to  use  tobacco. 

Dr.  J.  W.  Seaver,  Professor  of  Physical  Education  at 
Yale,  has  made  a  careful  study  of  the  influence  of 
tobacco  upon  the  bodies  and  minds  of  the  students. 
He  found  that  during  three  and  one  half  years  of 
undergraduate  life,  the  non-smokers  increased  in  height 
24  per  cent  more  than  the  smokers ;  in  girth  of  chest, 
26  per  cent  more ;  and  in  lung  capacity  77  per  cent 
more. 


276  THE   BODY  IN  HEALTH 

It  has  been  found  that  tobacco  smoking  in  a  boy 
affects  some  of  the  cells  at  the  base  of  the  brain  and 
so  interferes  with  the  breathing  and  the  action  of  the 
heart.  The  tissues  do  not  get  their  full  share  of 
oxygen,  and  the  blood  is  not  distributed  equally  to 
all  parts  of  the  body.  Any  of  the  work  of  the  body 
may  be  interfered  with  because  of  this. 

A  professor  in  the  Kansas  State  Agricultural  College 
recently  examined  the  condition  of  2500  school  boys 
who  smoked  cigarettes.  In  one  group  of  twenty-five 
school  boys  whose  average  age  of  beginning  to  smoke 
was  thirteen  years,  he  found  the  following  conditions : 
sore  throat,  4  ;  weak  eyes,  10  ;  pain  in  chest,  8  ;  short 
wind,  21  ;  stomach  trouble,  21  ;  pain  in  heart,  9. 

In  the  high  schools  in  Wisconsin,  it  was  found  that 
nearly  all  of  the  boys  who  were  dropped  because  of 
poor  work  or  who  were  expelled  for  one  cause  or  another 
were  smokers.  Those  who  used  tobacco  were  almost 
always  behind  those  who  did  not  use  it.  In  some 
places,  boys  under  sixteen  who  use  tobacco  in  any 
form  will  not  be  employed  in  any  kind  of  work.  Is 
this  right  ?  Why  ? 

That  many  boys  and  young  men  are  being  injured 
by  smoking  was  shown  in  the  military  examinations 
during  the  great  World  War.  The  examining  physicians 
had  to  refuse  a  very  large  proportion  of  those  who 
wanted  to  enlist  in  the  army  because  they  were  suffering 
from  "tobacco  heart"  caused  by  smoking. 

These  things  show  us  that  tobacco  is  another  of  the 


THE   BODY'S   ENEMIES  277 

deceiving  drugs  that  promises  happiness  and  brings 
trouble.  It  makes  slaves  of  its  young  victims,  while 
it  gradually  kills  them. 

HEALTH  PROBLEMS 

1.  If  you  can  do  so,  put  a  little  alcohol  diluted  one  half  with 
water  on  the  leaf  of  a  plant,  and  notice  what  happens  to  it. 

2.  Try  putting  some  alcohol  diluted  one  half  on  the  roots  of  a 
growing  house  plant,  and  notice  what  happens  to  it. 

3.  Why  is  it  impossible  for  a  drunken  man  to  reason  or  attend  to 
his  business  ? 

4.  Why  is  it  that  when  many  men  are  intoxicated  they  use 
vulgar  speech  which  they  would  not  use  when  they  are  sober  ? 

5.  Why  do  such  men  often  want  to  engage  in  a  brawl  ? 

6.  In  some  of  the  universities  there  are  delicate  instruments 
which  are  used  to  see  how  quickly  one  can  act  upon  a  sign  and  how 
quickly  he  can  choose  between  lines  of  action.     It  has  been  found 
that  alcohol  always  interferes  with  acting  quickly  and  choosing 
wisely.     Explain. 

7.  Why  will  a  man  on  an  athletic  team  be  instantly  dismissed 
if  he  is  caught  indulging  in  alcoholic  drinks  ? 

8.  Why  do  some  men  who  get  drunk  treat  their  families  bru- 
tally ? 

9.  Judges  say  that  most  crimes  are  due  to  the  use  of  alcohol. 
Should  you  expect  this  ?     Explain. 

10.  Is  there  any  law  in  your  community  which  forbids  people 
under  a  certain  age  to  use  tobacco  ?     Ought  there  to  be  such  a 
law  ?     Why  ?     A  school  board  in  Wisconsin  made  a  rule  recently 
that  no  pupil  in  a  school  could  smoke  outside  of  his  own  home. 
Why  did  the  board  make  such  a  rule  as  this  ? 

11.  In  many  of  the  high  schools  of  this  country,  a  boy  who 
smokes  can  not  be  on  any  of  the  teams  or  receive  any  honors  from 
the  school.     Why  has  this  rule  been  made? 


278  THE   BODY   IN   HEALTH 

12.  Sometimes  you  hear  men  say  that  after  they  have  stopped 
smoking  for  a  while  and  they  take  it  up  again  they  are  made  sick 
for  a  while  by  a  cigar  or  pipe.     Explain. 

13.  Why  is  it  that  many  smokers  do  not  consider  the  rights  or 
feelings  of  others,  but  blow  smoke  in  their  faces  in  cars,  on  the 
street,  and  so  on? 

14.  China  is  doing  everything  it  can  to  drive  opium  out  of  the 
country,  because  the  Chinese  say  it  has  held  back  their  people  for 
many  centuries.     Do  you  think  that  tobacco  may  have  much  the 
same  effect  upon  people  in  our  country,  if  we  do  not  get  rid  of  it  ? 

15.  Write  an  essay  on  this  topic:   "Why  Alcohol  and  Tobacco 
are  Enemies  of  the  Body." 

REVIEW  QUESTIONS 

1.  What  poisonous  substances  may  give  pleasurable  sensations 
for  the  moment  ? 

2.  To  what  family  does  alcohol  belong  ? 

3.  What  will  alcohol  in  a  pure  state  do  to  any  living  tissue 
with  which  it  comes  in  contact  ? 

4.  Describe  the  accident  which  happened  to  Alexis  St.  Martin 
and  the  study  that  was  made  of  his  stomach. 

5.  What  was  found   regarding  the  effects  of  alcohol  on  the 
stomach  of  St.  Martin  ? 

6.  How  does  alcohol  affect  the  nerves  ? 

7.  How  does  alcohol  affect  the  liver  ? 

8.  What  is  meant  by  " hob-nailed  liver"  ? 

9.  If  you  put  the  brain  in  alcohol,  what  change  will  take  place 
in  it  ? 

10.  Why  can  an  expert  tell  a  drunkard's  brain  in  the  dark  by 
the  sense  of  touch  alone  ? 

11.  What  happens  to  the  nerve  cells  when  alcohol  is  put  into  the 
blood  ? 

12.  How  is  it  possible  for  a  man  who  is  drunk  to  become  sober 
again  ? 


THE   BODY'S   ENEMIES  279 

13.  What  may  happen  to  the  nerve  cells  if  a  man  continues  to 
drink  beer,  whisky,  and  the  like  ? 

14.  Of  what  terrible  disease  of  the  mind  is  alcohol  often  the 
cause  ? 

15.  What  do  life  insurance  companies  say  about  the  use  of 
alcohol  ?     Will  they  insure  a  man  who  does  not  drink  liquor  for 
less  than  they  will  insure  one  who  does  ?     Why  ? 

1 6.  Is  it  right  to  speak  of  alcohol  as  a  deceiver  ?     How  does  it 
deceive  one  ? 

17.  What  did  the  French  government  find  about  the  effects  of 
tobacco  upon  the  nerves  of  the  people  of  France  ? 

18.  Why  was  a  law  passed  in  France  forbidding  the  students   of 
government  training  schools  to  use  tobacco  ? 

19.  What  has  Doctor  Seaver,  of  Yale  University,  found  regard- 
ing the  effects  of  tobacco  ? 

20.  Why  is  it  that  when  a  boy  smokes  there  is  likely  to  be  a 
disturbance  of  his  breathing  and  his  heart  ? 

21.  What  was  found  out  by  the  professor  in  the  Kansas  State 
Agricultural  College  about  the  effects  of  smoking  on  the  health  of 
boys  ? 

22.  What  was  found  regarding  the  use  of  tobacco  by  school 
boys  in  Wisconsin  ? 

23.  What  was  shown  regarding  the  effects  of  tobacco  on  boys 
and  young  men  during  the  World  War  ? 


CHAPTER  XVII 


THE  BODY'S  ENEMIES  —  DISEASE  GERMS 

IN  this  chapter,  we  must  bring  together  all  we  have 
learned  about  those  deadly  enemies  of  the  body,  disease 

germs,  and  add 
some  new  facts. 
When  there  is  an 
outbreak  of  disease 
in  a  community, 
some  of  the  people 
exposed  to  the 
germs  take  the 
disease,  become 
very  sick,  and  per- 
haps  die,  while 
others  escape  en- 
tirely. Why  do 
not  all.  the  people 
exposed  to  the 
germs  become 
sick  ? 

A  healthy  hu- 
man body  is  able  to  defend  itself  quite  well  against 
all  kinds  of  germs.  Only  when  they  attack  in 

280 


THE  GERMS  OF  MANY  DISEASES  CAN    BE    SEEN  AND 
STUDIED   WITH    THE    AID    OF   A    MICROSCOPE. 


THE   BODY'S   ENEMIES  —  DISEASE  GERMS     281 

overwhelming  numbers,  or  when  the  natural  de- 
fenses of  the  body  have  been  weakened,  are  they  able 
to  gain  a  foothold  in  the  body.  Yet  in  the  warfare 
that  is  constantly  going  on  between  mankind  and  these 
invisible  foes,  a  large  part  of  the  human  race  is  killed. 
What  are  some  of  the  reasons  for  this  ? 

You  know  already  that  when  we  speak  of  disease 
germs  we  refer  to  those  little  plants  (bacteria)  and 
animals  (protozoa)  that  are  capable  of  growing  in  the 
bodies  of  human  beings  and  animals  and  causing 
disease.  Where  are  these  most  likely  to  be  found  ? 

You  have  learned  that  the  germs  of  tuberculosis 
may  be  blown  about  in  the  dust  of  the  street  and 
that  typhoid  fever  germs  may  be  carried  by  water. 
Scarlet  fever  and  other  disease  germs  may  be  found  in 
milk.  Diphtheria  germs  have  been  found  on  drinking 
cups.  The  germs  are  conveyed  to  these  places  in  some 
way  from  the  bodies  of  persons  sick  with  these  dis- 
eases. The  only  place  where  the  disease  germs  can 
multiply  is  in  the  bodies  of  the  sick.  You  can  see, 
therefore,  why  it  is  of  the  utmost  importance  that  all 
material  coming  from  the  bodies  of  the  sick  should  be 
disinfected  or  destroyed  so  that  the  germs  may  not  be 
scattered  about  to  infect  other  people.  If  this  were 
always  done  as  it  should  be,  do  you  think  that  many 
diseases  might  be  completely  stamped  out  in  a  short 
time  ?  Mention  some  of  them. 

The  germs  of  different  diseases  have  different 
methods  of  getting  into  the  body.  To  know  the  ways 


282 


THE   BODY  IN  HEALTH 


in  which  they  are  most  likely  to  enter  may  help  us 
to  guard  against  them.  Some  may  be  introduced  by 
How  the  bites  of  insects.  A  certain  kind  of  mos- 

germs          quito  spreads  the  germs  of  malaria.     Another 
enter  the      kind  introduces  into  the  body  with  its   bite 
the  germs  of  yellow  fever.     Fleas  spread  the 
germs  of  plague.      It  has  been   found  that   infantile 

paralysis  has  in  some  cases  been 
caused  by  the  bite  of  the  stable 
fly.  Sometimes  pus-forming 
germs  work  their  way  into  the 
hair  follicles  and  sweat  glands 
of  the  skin  or  they  may  get  in 
through  scratches  or  wounds. 
The  germs  of  colds,  tuberculosis, 
pneumonia,  influenza,  and  other 
diseases  come  in  through  the 
air  passages.  Typhoid  fever 
and  cholera  germs  get  into  the  body  with  the  food. 
When  the  disease  germs  once  get  a  foothold  in 
the  body,  the  mischief  they  are  able  to  work  is  due 
to  two  things :  (i)  The  great  rapidity  with  which 
they  multiply ;  and  (2)  their  power  to  produce  deadly 
poisons. 

You  may  recall  how  the  cells  of  the  body  multiply, 

-  by    each    cell's    dividing    into    two.     Most    disease 

germs  multiply  in  the  same  way,  and,  as  you  already 

know,  at  a  very  rapid  rate.     The  germs  of  cholera, 

for  instance,  may  become  full  grown  and  divide  into 


A   DISEASE    CARRIER. 


THE   BODY'S   ENEMIES  —  DISEASE  GERMS     283 

two  in  twenty  minutes.  In  this  way  they  can  extend 
their  ravages  in  the  body  with  great  swiftness. 

The  weapon  used  by  our  germ  enemies  in  their 
attack  upon  the  body  is  the  deadly  poisons  which 
they  produce.  It  is  these  toxins,  as  they  are  called, 
which  are  very  violent  poisons,  that  really  cause  the 
disease  by  poisoning  the  cells  of  the  body.  Almost 
all  fevers  are  caused  by  these  germ-formed  poisons. 
Some  germs  produce  stupefying  poisons ;  others, 
irritant  poisons  ;  still  others,  paralyzing  poisons.  Each 
class  of  germ  develops  its  own  brand  of  poison. 

Even  when  a  person  is  in  good  health,  the  healing 
or  restoring  process  is  constantly  going  on  in  his  body 
in  order  to  keep  him  healthy.  When  one  has  _ 

it  -II-          i  11  How  the 

worked  until  he  is  exhausted,  he  must  recover  body 
from  his  fatigue  before  he  can  undertake  fresh  Defends 
work.     The   digestion   of  a   meal   leaves  the 
stomach   in   a   congested   state,   from  which   it   must 
recover   before   it   is    ready   to   digest    another   meal. 
The  body  is  being  continually  worn  by  its  work  and 
so  it  needs  constant  restoring.     This  work  is  done  by 
what  we  call   the  natural   forces  of  the  body  —  the 
power  of  the  body  to  heal  itself. 

The  healthy  body  is  also  able  to  defend  itself  against 
germs  in  a  variety  of  ways.  The  skin  is  an  outer 
defense  which  in  a  healthy  state  cannot  be  penetrated 
by  germs.  The  mucus  of  the  mouth  and  nose  has 
some  power  to  prevent  the  growth  of  germs  and  even 
to  destroy  them.  The  cells  which  cover  the  2000 


284  THE   BODY  IN  HEALTH 

square  feet  of  lung  surface  are  constantly  engaged  in 
capturing  and  destroying  germs.  The  gastric  juice  is 
a  powerful  germicide,  or  germ  killer,  capable  of  destroy- 
ing the  germs  of  cholera,  typhoid  fever,  and  any  other 
germs  that  are  likely  to  get  into  it.  The  white  cells  of 
the  blood  are  the  special  defenders  of  the  body  against 
germs  that  enter  the  tissues,  and  the  blood  serum  also 
has  the  power  to  destroy  germs. 

When,  through  the  weakening  of  the  natural  de- 
fenses, the  germs  are  able  to  gain  a  foothold  in  the  body, 
great  injuries  may  take  place.  The  germ  poisons 
irritate  or  paralyze  the  tissues,  and  cause  inflamma- 
tion, congestion,  pain,  and  other  disturbances.  A 
special  work  of  healing  is  then  necessary,  and  the  body 
has  to  rally  all  its  forces  to  meet  and  conquer  the  in- 
vading army.  This  it  does  in  two  ways:  (i)  By  in- 
creasing the  number  of  white  cells  ;  (2)  by  the  forma- 
tion of  special  germ-killing  substances  in  the  blood  and 
antitoxins  to  act  against  the  toxins  made  by  the  dis- 
ease germs. 

You  remember  how  the  white  cells  in  the  blood  seem 
to  be  attracted  to  the  germs  that  get  into  the  body 
and  how  they  inclose  or  swallow  them.  Then  ensues  a 
struggle  in  which  the  germ  tries  to  kill  the  corpuscle, 
and  the  corpuscle  tries  to  digest  and  kill  the  germ. 
The  life  of  the  person  in  whom  this  fight  is  going  on 
depends  upon  which  gets  the  victory,  the  corpuscles 
or  the  germs.  All  that  the  doctor  or  nurse  can  do  is 
to  help  the  body  to  summon  all  its  natural  forces,  and 


THE   BODY'S   ENEMIES -- DISEASE  GERMS    285 


to  try  as  far  as  possible  to  assist  the  little  soldiers  in 
their  fight. 

As  each  class  of  germs  has  its  own  particular  poison, 
so  the  body  produces  a  special  germ-killing  substance 
suited  to  the  particular  kind  of  germ  by  which  it  is 
being  attacked. 
You  know  there 
are  diseases,  such 
as  smallpox  and 
scarlet  fever,  which 
a  person  usually  has 
but  once.  A  person 
who  has  had  small- 
pox may  afterward 
go  among  people 
suffering  with  this 
disease  without  any 
danger  of  infection. 
He  has  become  im- 
mune to  that  dis- 
ease ;  that  is,  that 
particular  kind  of 
disease  germ  can  no 

.  I      PEOPLE  CAN  BE  MADE  IMMUNE  TO  CERTAIN  DIS- 

longer    grow    and  EASES  BY  VACCINATION. 

multiply    in    his 

body.  The  reason  for  this  seems  to  be  that  the  special 
substance  required  to  kill  that  kind  of  germ  remains 
in  his  blood  through  life  and  promptly  kills  any 
such  germs  that  may  enter.  Some  diseases  we  may 


286  THE   BODY  IN  HEALTH 

have  again  and  again,  because  the  germicidal,  or  germ- 
killing,  substance  for  those  particular  germs  quickly 
passes  out  of  the  blood. 

Since  we  are  in  constant  danger  of  attack  from  dis- 
ease germs,  it  is  necessary  to  be  constantly  on  guard 
against  them.  What  are  some  of  the  ways  Guarding 
in  which  we  may  be  protected  from  at-  against 
tacks  of  this  sort  ?  In  the  first  place,  by  dlsease-  ; 
means  of  public  hygiene  or  sanitation  we  may  protect 
ourselves.  The  health  and  sanitary  officers  in  a  com- 
munity may  be  looked  upon  as  a  sort  of  advance  guard 
or  scouting  party.  They  go  out,  armed  with  micro- 
scope and  test  tube,  to  spy  out  the  enemy,  —  to  find 
out  where  the  disease  germs  may  be  lurking  and  from 
what  point  they  are  likely  to  make  their  attack.  If 
possible,  they  destroy  them  before  they  have  a  chance 
to  do  any  mischief.  When  this  is  not  possible,  they 
warn  the  people  so  that  they  may  be  on  their  guard. 
They  compel  people  to  put  a  large  label  on  the  house 
when  any  one  inside  is  sick  from  some  infectious  dis- 
ease. They  examine  the  drinking  water  and  see  that 
there  is  a  pure  supply  or  that  the  people  are  warned 
when  it  contains  disease  germs  or  parasites.  They 
inspect  the  food  supplies  in  the  markets  and  stores 
and  order  any  that  is  diseased  or  unfit  for  food  to  be 
promptly  destroyed.  When  there  is  an  outbreak  of 
disease  in  a  community,  they  search  out  the  cause  and 
see  that  it  is  corrected. 

In  the  war  between  Russia  and  Japan  (1904-1905) 


THE   BODY'S   ENEMIES  —  DISEASE  GERMS     287 

the  sanitary  officers  were  always  sent  out  in  advance 
with  the  army  scouts.  They  tested  all  the  wells  and 
labeled  them  so  that  the  soldiers  would  know  if  the 
water  was  fit  for  drinking.  They  went  with  the  forag- 
ing parties  and  sampled  all  the  food,  fruit,  and  vege- 
tables sold  along  the  line  of  march.  They  examined 
the  sanitary  conditions  of  every  town  before  the  army 
arrived.  If  there  was  any  danger  from  infection,  the 
place  was  quarantined  and  guarded.  They  were  in 
the  camps,  teaching  the  soldiers  how  to  protect  them- 
selves. 

As  a  result  of  this  careful  attention  to  hygiene,  the 
Japanese  army  lost  scarcely  a  man  from  preventable 
disease.  In  the  Spanish  American  war,  the  death  rate 
from  preventable  disease  was  70  per  cent,  --  only 
268  men  were  killed  by  bullets,  while  3862  died  in  the 
hospitals.  This  will  give  you  some  idea  of  how  much 
may  be  done  by  public  hygiene  to  guard  people  from 
disease. 

As  we  have  public  hygiene,  so  we  must  have  domestic 
hygiene.    You  will  recall  that  house  dust  is  very  danger- 
ous.    It  contains  germs  brought  in  from  the  Domestic 
street  on  the  feet,  or  that  have  floated  in  the  hygiene, 
air,  particularly  those  of  pneumonia  and  tuberculosis, 
two  most  dangerous  communicable  diseases.     Sweep- 
ing and  dusting  are  sometimes  done  in  a  way  that  only 
stirs  up  the  germs,  and  keeps  them  floating  about,  in- 
stead of  getting  rid  of  them.      The  vacuum  cleaner, 
which  sucks  up  all  the  dust  and  scatters  none  of  it,  is 


288  THE   BODY   IN   HEALTH 

by  far  the  best  method  of  removing  dust  from  curtains 
and  carpets.  The  dustless  duster  or  a  damp  cloth  will 
remove  the  dust  which  the  ordinary  dry  duster  only 
stirs  up. 

The  kitchen,  pantry,  sinks,  closets,  and  cellars  need 
frequent  cleaning.  Fermenting  and  decaying  materials 
are  always  a  source  of  germs,  and  they  should  not  be 
allowed  to  accumulate.  Cesspools  should  be  situated 
far  from  the  house  and  should  be  water-tight  so  that 
the  soil  about  the  house  cannot  become  polluted  with 
the  drainage.  Stables  and  animal  pens  should  also 
be  at  a  distance  from  the  house  and  should  be  kept 
clean. 

Sunlight  is  Nature's  great  disinfectant.  It  destroys 
germs  brought  in  contact  with  it.  So  we  should  admit 
the  sunlight  to  every  room  in  the  house,  closets  in- 
cluded, if  possible.  Let  it  do  its  disinfecting  work  in 
every  nook  and  corner  of  the  home.  Fire  is  the  best 
of  all  disinfectants.  Germ-producing  matter  should 
be  burned  whenever  possible.  Ordinary  boiling,  con- 
tinued for  half  an  hour,  will  destroy  all  sorts  of  danger- 
ous germs. 

Of  more  importance  than  either  public  or  domestic 
hygiene  is  personal  hygiene  —  the  acquiring  of  those 
Personal  habits  which  will  keep  the  germs  out  of  the 
hygiene.  body  and  will  keep  up  the  natural  power  of  the 
body  to  kill  them  if  they  should  enter. 

Mention  some  personal  habits  which  may  be  a  means 
of  introducing  germs  into  the  body.  Think  of  the  ways 


THE   BODY'S  ENEMIES  —  DISEASE  GERMS    289 

in  which  the  hands  may  gather  germs  in  the  course 
of  a  day,  —  from  door  knobs,  car  straps,  money,  and 
the  hands  of  other  persons.  Should  there  be  disease 
germs  among  them,  these  may  get  into  the  mouth  with 
the  food  or  into  the  eyes  if  they  are  rubbed.  The 
simplest  and  easiest  method  of  disinfecting  the  hands 
is  by  a  thorough  washing  with  soap.  This  is  especially 
necessary  before  eating.  Drinking  from  a  cup  used 
by  others  is  another  way  by  which  disease  germs  may 
get  into  the  body.  At  school  or  when  traveling  it  is 
always  best  to  carry  a  private  cup.  Also  avoid  putting 
into  the  mouth  pencils,  money,  or  other  articles  that 
have  been  handled  by  others. 

Even  with  all  the  precautions  that  we  have  men- 
tioned, it  is  not  possible  to  keep  the  body  entirely  free 
from  disease  germs.     There  are  usually  present  Keeping 
in  the  body  germs  capable  of  producing  dis-  up  body 
ease,  waiting  for  a  favorable  opportunity  to  resistance- 
attack.     These  are  not  to  be  feared  so  long  as  the  body 
is  in  such  a  healthy  condition  that  its  natural  defenses 
are  active.     But   to   let   the  body  get   run   down  or 
weakened  by  bad  habits  is  to  open  the  gates  to  the 
enemy.     This  may  be  done  by  lack  of  exercise,   bad 
food,    overeating,    insufficient    sleep,    bad   ventilation, 
overwork,  or  by  the  use  of  alcohol.     Show  why  in  each 
case. 

At  the  time  that  Doctor  Hodge  made  the  experi- 
ments with  his  dogs,  there  was  an  epidemic  in  the  city 
of  a  disease  to  which  dogs  are  subject.  This  gave  the 


290  THE   BODY  IN  HEALTH 

doctor  an  opportunity  to  see  what  effect  alcohol  would 
have  upon  their  resisting  power.  Nig  and  Topsy, 
who  had  no  alcohol,  were  scarcely  sick  at  all,  and 
quickly  threw  off  the  disease,  but  both  Bum  and 
Tipsy,  who  were  given  alcohol  regularly,  had  the  dis- 
ease in  a  very  severe  form,  and  were  so  sick  that  they 
were  saved  only  by  Doctor  Hodge's  careful  nursing. 

When  one  country  is  expecting  war  with  another  the 
standing  army  is  carefully  inspected  to  see  that  all  its 
soldiers  are  well  equipped  and  in  good  fighting  trim. 
Care  is  also  taken  that  the  reserve  forces  shall  be 
ready  if  called  upon.  It  is  just  as  important  for  us, 
subject  as  we  are  to  the  attacks  of  germs,  to  keep  our 
standing  army  of  body  defenders  in  good  condition 
and  our  reserve  forces  ready  to  be  drawn  upon  if 
necessary. 

HEALTH  PROBLEMS 

1.  What  is  the  meaning  of  the  natural  defenses  of  the  body? 
Is  the  term  "  natural  defenses  "  appropriate  ?     Why  ?     Mention 
some  of  these  natural  defenses. 

2.  How  do  nurses  and  doctors  generally  avoid  taking  the  disease 
from  the  sick  person  whom  they  treat  ? 

3.  In  some  cities  they  are  building  bungalows  on  the  roofs  of 
skyscrapers.     The  people  who  build  these  plan  to  live  in   them 
just  as  other  people  live  in  houses  built  on  the  ground.      If  you 
were  living  in  Chicago  or  New  York  or  any  other  large  city,  do  you 
think  it  would  be  more  healthful  to  live  in  one  of  these  bungalows 
than  in  an  ordinary  house  ?     Why  ? 

4.  Give  arguments  for  and  against  the  statement :  "It  is  the 
duty  of  every  one  to  keep  well."     Should  not  every  person  be  free 
to  catch  a  germ  disease  if  he  wished  to  do  so  ?    Why  ? 


THE   BODY'S   ENEMIES  —  DISEASE  GERMS    291 

5.  Suppose  some  one  member  of  the  family  is  always  catching 
colds  and  coughs.     What  may  be  the  explanation  of  this  ?     How 
should  such  a  person  be  treated  ? 

6.  If  you  were  living  in  a  malarial  country,  what  gateway  of 
germs  to  the  body  would  you  guard  particularly  ?     Why  ? 

7.  Suppose   there  was  an  epidemic  of  yellow  fever  in  your 
community,  what  gateway  to  the  body  would  you  guard  particu- 
larly ?    Why  ?     Consider  in  the  same  way  an  epidemic  of  typhoid 
fever  and  of  diphtheria. 

8.  Why  did  Nature  put  poison  into  the  bite  of  a  snake  ?     Why 
did  Nature  give  germs  the  power  to  generate  toxins  which  poison 
the  cells  of  the  body  ? 

9.  Give  an  instance  that  you  have  observed  of  the  powers  of 
the  body  to  restore  itself.     Also  give  an  instance  of  the  power  of  the 
body  to  heal  itself  from  some  severe  injury  or  illness. 

10.  You  often  hear  a  person  say;    "I  was  all  run  down,  and  I 
caught  a  cold."     Just  what  does  he  mean  by  this  ?     Do  people 
catch  coughs  and  colds  more  frequently  when  they  are  "run  down" 
than  at  other  times  ?     Why  ? 

11.  Speak  of  habits  you  observe  in  people  which  are  likely  to 
weaken   their   "natural  defenses".     Are  such   people    often  ill? 
Why? 

12.  Mention  some  common  diseases  which  a  person  may  have 
over  and  over  again.     Mention  diseases  which  he  is  not  likely  to 
have  but  once  in  a  lifetime,  and  explain. 

13.  Show  how  the  sanitary  officers  in  a  community  are  much 
like  the  scouts  and  pickets  in  an  army.     Suppose  the  scouts  and 
pickets  should  not  do  their  duty,  what  might  happen  to  the  army  ? 
Might  it  be  the  same  way  in  a  community  if  sanitary  officers  were 
neglectful  of  their  duty  ? 

14.  Suppose  we  could  get  rid  of  all  diseases  caused  by  germs. 
Would  there  be  any  diseases  left  ?     If  so,  mention  some  of  them 
and  tell  how  they  would  be  caused. 


292  THE  BODY  IN  HEALTH 

REVIEW  QUESTIONS 

1.  When  are  germs  likely  to  get  a  foothold  in  the  body  ? 

2.  Do  germs  ever  win  in  their  war  with  the  human  race  ?     Why  ? 

3.  What  are  the  names  used  for  disease  germs?     What  does 
this  name  mean  ? 

4.  How  may  the  germs  of  tuberculosis  be  spread  ?    The  germs 
of  typhoid  ?     Diphtheria  ? 

5.  What  are  the  breeding  grounds  for  germs  that  make  people 
sick  ? 

6.  How  do  insects  spread  disease  ? 

7.  How  do  the  germs  of  colds,  influenza,  and  other  diseases  get 
into  the  body  ? 

8.  What  are  the  two  ways  in  which  germs  work  their  mischief 
in  the  body  ? 

9.  How  do  disease  germs  multiply  ?     How  rapidly  do  the  germs 
of  cholera  multiply  ? 

10.  What  are  the  weapons  which  germ  enemies  use  to  attack 
the  body  ? 

11.  What  is  the  meaning  of  toxins  ? 

12.  How  does  the  body  defend  itself  against  its  germ  enemies  ? 

13.  What  has  nature  provided  in  the  body  to  kill  disease  germs  ? 
How  do  the  poisons  made  by  the  germs  work  upon  the  body  ? 

14.  What  are  the  chief  defenders  of  the  body  against  disease 
germs  ? 

15.  What  can  the  corpuscles  and  antitoxins  do   to  help  the 
body  in  its  fight  against  germs  ? 

16.  What  does  it  mean  to    become    immune    to    a    disease  ? 
Why  does  a  person  have  smallpox  only  once  in  a  lifetime  ? 

17.  What  are  the  means  of  guarding  against  germ  enemies  ? 

1 8.  Tell  about  the  care  which  the  Japanese  took  to  protect 
their  soldiers  against  germ  enemies. 

19.  What  is  meant  by  domestic  hygiene  ?     What  are  some  of 
the  ways  in  domestic  hygiene  for  guarding  against  disease  germs  ? 


THE   BODY'S   ENEMIES  —  DISEASE  GERMS      293 

20.  Mention  several  good  ways  to  kill  germs. 

21.  What  is  meant  by  personal  hygiene  ? 

22.  Mention  different  sorts  of  habits  of  life  which  will  enable 
one  to  fight  disease  germs  successfully. 

23.  What  does  it  mean  to  keep  up  body  resistance  ? 

24.  What  does  it  mean  to  "open  the   gates    to    the   body's 
enemies"  ? 

25.  Mention  various  ways  in  which  our  body  defenders  can  be 
kept  in  good  fighting  trim  so  as  to  ward  off  disease. 


CHAPTER  XVIII 
"  CATCHING  "  DISEASES 

No  person  would  purposely  plan  to  make  a  friend 
sick.  Yet  it  often  occurs,  without  any  intent  on  his 

part,  that  one  who  is  ill,  through  being  with 
danger  other  persons,  causes  them  to  become  ill  too. 
of  con-  This  is  because  the  disease  he  has  is  communi- 
(Hseases  cable,  or  can  be  passed  from  one  person  to 

another.  In  other  words,  it  is  a  "catching" 
or  contagious  disease.  Smallpox,  measles,  scarlet  fever, 
diphtheria,  chicken  pox,  mumps,  and  whooping  cough 
are  all  communicable  or  contagious  diseases.  A  child 
who  has  any  one  of  these  is  a  danger  to  other  children 
until  he  is  entirely  well,  even  though  he  may  himself 
not  feel  sick.  Very  severe  cases  often  result  from 
coming  in  contact  with  one  of  these  diseases  in  a  mild 
form. 

Those  who  guard  the  health  of  the  people  have  made 
it  a  law  that  persons  having  a  communicable  disease 
Quaran-  shall,  as  soon  as  this  is  known,  live  quite  apart 
****'  from  other  people.  This  is  called  a  quarantine, 

and  it  is  necessary  in  order  to  prevent  others  from 
taking  the  same  disease.     With  many  children,  quaran- 

294 


"CATCHING"   DISEASES 


295 


tine  is  the  hardest  part  of  the  illness,  since  they  must 
stay  at  home,  and  none  of  their  playmates  may  come 
to  see  them.  But  when  one  thinks  of  the  risk  to  others, 
he  feels  it  is  quite  right  that  he  should  not  see  them. 

My  young  friend  Georgia,  at  school  one  day,  com- 
plained of  hav- 
ing a  sore  throat. 
Her  teacher  at 
once  sent  her 
home,  although 
the  girl  said  she 
did  not  really  feel 
sick,  and  she 
begged  to  be  al- 
lowed to  remain. 

The     teacher     did          GEORGIA  COMPLAINED  IN  SCHOOL  ONE  DAY  OF 

j  i  HAVING   A    SORE   THROAT. 

not  send  her  away 

because  of  her  misfortune  in  having  a  sore  throat,  but 
as  a  precaution  for  the  rest  of  the  pupils.  Did  the 
teacher  do  the  right  thing  to  send  Georgia  home  ? 

The  teacher  knew  that  sore  throat  is  often  a  danger 
signal,  and  such  it  proved  to  be  in  Georgia's  case. 
Soon  after  reaching  home,  she  began  to  feel  Howa 
hot   and  feverish;    and   her  mother  called  a  "culture" 
physician.     When    the    physician    discovered  istaken- 
that  her  throat  was  sore,  he  took  a  small  wooden  stick 
from  his  case.     Around  one  end  of  this  he  wound  some 
sterile  cotton,   that    is,   cotton    free    from    all    germs, 
and  made  a  swab.     With  the  swab  he  wiped  the  little 


296  THE   BODY  IN  HEALTH 

girl's  throat.  Afterward  he  put  the  substance  wiped 
off  on  the  kind  of  soil  upon  which  germs  like  best  to 
grow,  —  that  is,  upon  a  "culture"  plate.  If  Georgia 
had  diphtheria,  as  the  doctor  feared,  this  "culture" 
would,  he  knew,  show  it  in  a  few  hours.  Diphtheria 
is  always  caused  by  germs.  These  germs  grow  on 
the  mucous  membrane  of  the  mouth  and  throat.  They 
are  so  tiny  they  cannot  be  seen  with  the  eye  alone. 
But  if  some  of  them  are  wiped  off,  and  planted  on 
"culture"  soil,  a  microscope  will  reveal  them  as  they 
grow.  If  the  throat  from  which  the  culture  is  taken 
has  no  diphtheria  germs,  this,  too,  will  be  shown. 

The  doctor  told  Georgia's  mother  that  until  he 
could  make  a  report  on  this  case,  she  had  best  put 
Georgia  in  some  room  as  remote  as  possible  from  those 
occupied  by  other  people,  and  to  take  out  of  it  all  but 
necessary  furniture.  When  Georgia's  father  built  their 
cottage,  he  made  one  room  in  the  upper  story  that 
opened  upon  a  covered  porch.  It  was  also  connected 
with  a  small  bathroom.  There  were  three  nice  win- 
dows, too,  so  there  could  be  plenty  of  sunshine  and 
fresh  air.  The  room  was  at  the  end  of  a  hall,  and  the 
family  called  it  their  "hospital  corner,"  because  in 
times  of  illness  it  could  be  fitted  up  very  well  for  a 
sick  room. 

Georgia  was  put  in  this  room  for  the  night,  after 
her  mother  had  taken  out  all  the  extra  things.  In 
the  morning,  the  culture  taken  from  her  throat  showed 
for  sure  that  Georgia  had  diphtheria,  and  the  doctor 


CATCHING"  DISEASES 


297 


said  she  must  not  go  from  the  "hospital  corner"  to 
any  other  part  of  the  house,  and  no  one  but  the  nurse 
and  himself  could  be  allowed  in  the  room  with  her. 
To  prevent  the  risk  of  any  other  child's  entering  the 
room  unawares,  the  nurse  kept  the  door  locked. 


GEORGIA  ON  THE  PORCH  —  THE  "HOSPITAL  CORNER." 

Diphtheria  is  a  very  "catching"  disease.     Now  that 
it  was  certain  diphtheria  germs  were  making  Georgia 
ill,  the  doctor  said  that  she  and  every  one  in  Antitoxins 
the  house   should   have  a  dose  of  antitoxin  and  their 
(anti  means  opposed   to,  and  toxin,  poison),  l 
a  remedy  that  works  against  the  poison  which  diph- 
theria germs  always  make  in  the  body. 


298 


THE   BODY  IN  HEALTH 


It  is  only  within  recent  years  that  it  has  been  possible 
to  secure  this  remedy.  Before  its  use,  only  about  one 
half  of  those  who  had  the  disease  in  severe  form  got 
well.  But  now  thousands  of  lives  are  saved  by  the 
employment  of  antitoxin.  The  more  promptly  it  is 
given,  the  better  the  results.  Where  it  is  used  within 
the  first  twenty-four  hours  of  illness,  there  is  a  loss  of 
only  one  life  in  a  thousand  cases.  Do  you  not  think 
every  one  should  make  use  of  antitoxin  when  he  is 

in  any  danger 
from  d  i  ph- 
theria  ? 

It  happens 
quite  often  that 
a  person  hav- 
ing diphtheria 
germs,  al- 
though not  at 
all  sick  himself, 
gives  the  dis- 
ease to  others. 
Such  a  person 
is  called  a  car- 
rier and  is  a 
danger  to  all 
his  friends  so 
long  as  he  has 
the  germs.  His  own  body  makes  antitoxin  enough  to 
defend  itself,  but  that  does  not  mean  safety  for  other 


THE  PHYSICIAN  PUT  UP  THIS  SIGN  ON  GEORGIA'S  HOUSE. 
WHY? 


"CATCHING"   DISEASES  299 

people.  In  some  cities,  when  a  case  of  diphtheria  occurs 
in  a  school,  cultures  are  taken  from  the  throats  of  all 
in  that  room  in  order  to  find  who  the  carrier  may  be. 
Carriers  need  to  be  quarantined,  and  have  the  germs 
in  their  throats  destroyed  the  same  as  in  the  case  of  a 
person  who  is  actually  sick  with  the  disease.  Why  ? 

In  the  case  of  Georgia,  the  health  officers  had  been 
notified  of  her  illness,  and  a  red  placard  was  put  on 
the  door,  warning  all  who  came  that  way  not 
to  enter.     Why  ?     A  notice  was  placed  where  cautions 
the  milkman  could  see  it  telling  him  not  to  observed 
leave  bottles  but  to  pour  the  milk  into  a  dish 
placed    specially   for  him.     Why  ?     A  poster 
placed  indoors  gave  directions  to  the  family  as  to  how 
they  must  care  for  themselves  and  for  the  diphtheria 
patient. 

Some  of  the  things  it  said  were  :  — 

"Diphtheria  is  always  dangerous  and  easily  given  to  others. 
It  is  catching  from  the  mildest  form.  .  Those  not  sick  enough  to 
be  in  bed  give  the  disease  to  others  oftener  than  the  very  sick. 

"Diphtheria  patients  must  not  leave  the  house  until  the  Depart- 
ment of  Health  removes  the  warning  card.  Neither  may  people 
living  in  the  house  go  in  and  out.  Inmates  of  the  house  must 
stay  indoors. 

"  Visitors  are  not  allowed. 

"Groceries  and  milk  must  be  left  at  the  door. 

"School  children  and  others  must  stay  at  home.  No  one  living 
in  the  house  is  allowed  to  go  to  church,  Sabbath  school,  or  to  other 
public  places. 

"Do  not  let  the  patient  spit  on  the  floor. 


300  THE  BODY  IN  HEALTH 

"Spit  and  nose  discharges  will  give  the  disease  to  others,  and 
should  be  caught  on  cloths,  and  burned  immediately. 

"Do  not  kiss  the  patient. 

"After  touching  the  patient  or  anything  he  handles,  always 
wash  your  hands. 

"Everything,  —  letters,  laundry,  bedding,  books,  magazines, 
papers,  and  clothing  must  be  disinfected  before  they  are  taken 
out  of  the  house. 

"Everything  used  in  the  sick  room,  such  as  knives,  forks, 
spoons,  dishes,  books,  playthings,  handkerchiefs,  towels,  sheets, 
pillow  slips,  clothing,  flowers,  and  remnants  of  food  must  be 
disinfected  before  being  taken  from  the  room." 

To  disinfect  an  article,  you  will  remember,  means 
to  do  something  to  it  that  will  kill  all  the  germs  on  it. 
As  we  learned  in  Chapter  IX,  there  are  several  ways 
of  doing  this.  For  instance,  any  article  which  will  not 
be  harmed  by  boiling  may  be  disinfected  in  that  way. 
So  on  a  gas  plate  in  the  bathroom,  Georgia's  nurse 
kept  a  tin  boiler  full  of  water  just  at  the  boiling  point. 
All  the  dishes  and  everything  which  Georgia  used  or 
touched  were,  as  soon  'as  she  was  through  with  them, 
put  into  this  water,  and  boiled  for  twenty  minutes. 

When  boiling  is  not  convenient,  a  metal  tub  may  be 
filled  with  some  solution  which  the  doctor  will  order, 
and  all  articles  may  be  soaked  in  it  for  a  time. 

One  thing  is  to  be  specially  remembered  whenever 
a  person  has  a  communicable  disease :  nothing  must 
ever  be  allowed  to  leave  the  sick  room  without  first  killing 
the  germs  on  it  by  thorough  disinfection. 

Georgia's  father  constructed  a  very  good  kind  of 


"CATCHING"   DISEASES  301 

dumb  waiter  by  means  of  which  he  might  send  meals 
up  to  the  sick  room.  First,  he  attached  a  small  chain 
to  a  large  tin  bread  box.  Then  by  fastening  a  pulley 
to  the  porch  railing  arid  adjusting  the  chain  on  it, 
it  could  be  raised  and  lowered  with  ease.  The  nurse 
opened  the  box  on  the  porch  outside  the 
door  and  emptied  all  foods 
into  the  special  dishes  kept 
there  for  Georgia's  use  and 
her  own.  Then  she  told  the  THE  KIND  THAT 

TYPHOID  FEVER      Qne   bdow   to   lower    the   box          CAUSE  TUBER- 

GERMS.  ,—.  ,  f    ,  CULOSIS. 

I  he  nurse  was  always  careful 

to  disinfect  her  hands  before  touching  the  box  or  its 
contents,  so  that  not  a  germ  might  find  its  way  to  the 
room  below. 

The  doctor  was  quite  at  a  loss  to  know  where  Georgia 
could  have  got  diphtheria  germs,  as  no  "car- 
riers"   had    been  found.     There    was    not  a 
case  in  that  town,  and  there  had  been  none  carried  in 
for  a  long  time.     Neither  had  Georgia  been  ^°rgia's 
away  on  any  visits. 

"Isn't  it  odd  that  my  Cousin  Ellen  should  be  having 
the  same  disease  that  I  am,"  said  Georgia  one  morning 
during  the  doctor's  visit. 

"  Where  does  your  cousin  live  ?"  inquired  the  doctor. 

"Way  up  in  Canada,"  replied  the  little  girl. 

"Then  how  do  you  know  she  has  been  sick  ?" 

"Oh,  we  write  letters  to  each  other.  She  wrote  me 
that  she  was  having  to  stay  out  of  school  because  she 


302  THE   BODY  IN  HEALTH 

had  been  ill  with  diphtheria.  It  is  just  queer  that  the 
same  thing  has  happened  to  both  of  us." 

"How  long  since  you  got  that  letter  ?" 

"Oh,  about  two  weeks  ago,"  replied  Georgia. 

"Well,"  said  the  doctor,  "it  does  not  seem  at  all 
queer  to  me.  It  is  plain  enough  now  that  the  germs 
which  are  causing  you  so  much  unpleasantness  came  to 
you  sealed  up  in  your  cousin's  letter.  The  strange 
thing  is  that  her  people  should  permit  her  to  send 
letters  while  she  was  ill  with  a  '  catching '  disease." 

"I  guess,  perhaps,  they  didn't  know  about  it,"  said 
Georgia,  "for  Cousin  Ellen  wrote  us  that  they  would  not 
let  her  go  out  at  all,  so  she  was  going  to  drop  her  letter 
out  of  the  window  and  ask  the  neighbor  girl  to  post  it." 

"It  would  not  surprise  me  if  the  neighbor  girl,  too, 
took  diphtheria  from  that  letter,"  said  the  doctor. 
"Diphtheria  germs  pass  from  the  sick  to  the  well  so 
easily  that  everything  touched  by  the  patient  is  dan- 
gerous until  the  germs  on  it  are  killed.  And,  too, 
these  germs  live  a  long  time." 

A  little  boy  I  knew  died  from  diphtheria.    His  mother, 

out  of  fondness  for  him,  kept  his  picture  blocks  and 

books  and  toys  in  a  trunk  which  she  stowed 

Animals  .          ,  Tr  r  * 

and  play-  away  m  the  attic.  Years  afterward,  some 
things  other  little  children  playing  in  the  attic  found 
may  cany  tnese  playthings,  and  from  them  got  the  germs 
that  made  both  of  them  very  ill  with  diphtheria. 
These  facts  and  many  similar  ones  have  made  it  plain 
that  the  greatest  care  must  be  taken  with  regard  to 


"CATCHING"   DISEASES  303 

all  the  things  that  come  into  contact  with  those  who 
are  ill  with  diphtheria.  The  same  is  true  in  respect 
to  other  catching  diseases.  So  you  see  it  is  best  always 
to  do  exactly  what  the  health  boards  and  those  who 
make  a  study  of  these  diseases  tell  us,  even  though  it 
is  not  very  pleasant  at  the  time. 

"May  I  have  my  dolly  to  play  with,  while  I  am  in 
quarantine  ?"  asked  Georgia. 

"You  may  have  anything  you  want  provided  you 
are  willing  that  it  should  be  burned  when  you  get 
well,"  replied  the  doctor. 

"Oh,  when  shall  I  be  well,  then  ?"  she  continued. 

"When  the  cultures  from  your  throat  show  that  you 
no  longer  have  diphtheria  germs/'  was  the  doctor's 
answer.  "No  one  can  tell  just  how  long  that  may  be, 
but  you  can  help  things  along  by  cheerfully  taking 
your  treatments  and  doing  as  your  nurse  tells  you." 

"And  does  everything  I  play  with  have  to  be 
burned  ?"  she  asked  again. 

"Anything  that  can  be  boiled  without  harm  can  be 
saved,"  said  the  doctor.  " There  are  other  ways  in 
which  some  things  can  be  made  safe,  but  in  general  it 
will  be  wiser  to  bring  nothing  up  here  that  you  will 
afterward  need  or  care  especially  for.  Your  nurse 
knows  so  many  nice  things  to  do,  you  will  not  miss 
your  dolly,  I  am  sure." 

Just  then  the  barking  of  a  dog  below  called  Georgia's 
attention  to  her  pet,  and  she  asked,  "Why  doesn't 
somebody  open  the  door  for  Gyp  ?" 


3o4  THE   BODY  IN  HEALTH 

"Gyp  is  in  quarantine,  too,"  said  the  doctor.  "He 
lives  in  the  carriage  house  now.  It  would  be  unsafe 
to  allow  him  in  the  house  while  there  are  diphtheria 
germs  about.  Animals  as  well  as  human  beings  take 
the  disease.  Even  if  Gyp  did  not  catch  it  himself, 
he  might  be  the  means  of  giving  it  to  some  person, 
for  the  germs  would  get  in  his  hair,  and  he  would 
scatter  them  wherever  he  went.  He  is  made  quite 
comfortable  and  given  plenty  to  eat,  but  he  doesn't 
like  to  be  shut  out  any  better  than  you  like  to  be  shut 

Every  day  a  cot  was  placed  in  a  quiet  corner  of  the 
porch.  On  it  Georgia  was  allowed  to  lie  out  of  doors 
where  she  could  watch  all  that  was  going  on  in  nature 
around  and  breathe  the  fresh  air. 

When  she  was  able  to  sit  up,  a  large  shallow  pan  of 
sand  placed  on  a  bedside  table  afforded  her  many 
pleasant  hours  of  play.  Out  of  it  she  made  a  farm 
with  valleys  and  hills,  rivers  and  lakes.  For  trees  she 
planted  green  twigs.  A  cardboard  house  and  barns, 
fences  of  toothpicks,  and  paper  men,  women,  children, 
and  animals  made  it  seem  quite  real. 

At  other  times  the  sand  pan  was  an  athletic  field 
where  paper  boys  played  ball,  or  a  park  with  flower 
beds,  and  winding  paths,  with  cages  of  wild  animals. 
Again  it  became  a  model  town  with  broad  streets,  on 
which  paper  automobiles  and  trolley  cars  were  seen. 
So  many  and  varied  were  the  things  that  could  be 
made  with  that  sand  pan  that  Georgia  quite  forgot 


"CATCHING"   DISEASES 


305 


she  was  in  quarantine ;  and  she  was  really  a  little  bit 
sorry  when  one  morning  the  doctor  said  to  her,  "You 
have  a  clean  throat,  and  to-day,  when  your  nurse  has 
given  you  a  cleansing  bath  all  over,  including  your 
hair,  you  may  put  on  clean  clothing  and  go  down 
stairs." 

"May  I  go  to  school  to-morrow  ?"  she  asked. 

"Not  to-morrow,  but  in  a  few  days,"  was  the  answer. 
"Culture  tests  must  be  made  again.  The  house,  too, 
must  first  be  cleansed  of  germs  so  that  you  will  carry 
none  to  school." 

Years  ago  people  understood  little  about  germs,  and 
their  part  in  the  cause  of  diseases.  They  knew  that 
certain  diseases  were  "catching,"  and  that  these 
rarely  attacked  the  same  individual  twice.  It  was  a 
common  belief  that  everybody  must  have  measles, 
scarlet  fever,  whooping  cough,  chicken  pox,  and 
mumps,  and  the  earlier  in  life  each  person  took  his 
turn  the  better  it  would  be  for  him.  Little  care  was 
taken  to  avoid  diseases,  and  sometimes  children  were 
sent  to  visit  the  sick  in  order  to  catch  their  disease. 
I  suppose  you  do  not  need  to  be  told  that  very  many 
lives  were  lost  through  such  ignorance. 

In  these  days  it  is  known  that  children  are  likely  to 
grow  up  stronger  and  in  better  health  if  they  do  not 
have  these  diseases.  It  is  known,  too,  that  if  ever 
they  have  the  misfortune  to  catch  any  of  them,  the 
older  they  are  at  the  time  the  better  able  they  will  be 
to  fight  the  germ  poison  of  the  disease. 


306  THE   BODY  IN  HEALTH 

All  that  has  been  said  with  reference  to  avoiding 
diphtheria  and  preventing  the  spread  of  the  disease  by 
disinfection  and  other  measures  applies  equally  well 
to  nearly  all  other  contagious  diseases,  the  most  com- 
mon of  which  are  typhoid  fever,  scarlet  fever,  measles, 
mumps,  chickenpox,  German  measles,  smallpox,  whoop- 
ing cough,  influenza,  and  pneumonia. 

Typhoid  fever  is  generally  communicated  through 
water  which  has  been  polluted  by  the  bowel  discharges 
or  other  excretions  of  persons  suffering  from 
av°7d°  the  disease.  When  water  was  generally  ob- 
spreading  tained  from  dug  wells,  typhoid  fever  was  very 
contagious  common  because  the  water  of  the  wells  became 
infected  by  the  seepage  from  vaults  or  cess- 
pools, and  sometimes  from  leaky  sewers. 

Most  cities  are  now  provided  with  public  water 
supplies  which  are  carefully  watched  and  guarded 
against  infection,  and  the  result  has  been  a  great  falling 
off  in  the  number  of  deaths  from  typhoid  fever.  At 
the  present  time  ten  to  twenty  per  cent  of  the  cases 
of  this  disease  are  found  to  be  due  to  infected  milk. 
In  a  small  town  in  California,  of  twenty-five  persons 
who  ate  ice  cream  at  a  picnic  twenty-three  had  typhoid 
fever  and  several  died.  In  this  case,  the  ice  cream 
was  prepared  by  a  woman  who  two  weeks  before  had 
been  sick  with  typhoid  fever. 

Two  epidemics  of  typhoid  fever  which  occurred  in 
Iowa  were  found  to  be  due  to  the  use  of  butter  made 
from  infected  cream.  In  these  cases,  it  was  shown  that 


"CATCHING"   DISEASES  307 

the  cream  was  obtained  from  dairies  where  one  or  more 
persons  in  the  family  were  sick  with  typhoid  fever. 
The  cream  was  doubtless  contaminated  by  flies  which 
visited  it  after  having  been  in  contact  with  the  bowel 
discharges  of  sick  persons.  This  shows  the  importance 
of  disinfecting  such  discharges  at  once  and  never  ex- 
posing them  in  such  a  way  that  flies  may  come  in 
contact  with  them. 

A  good  method  of  disinfection  is  to  pour  upon  the 
discharges  four  times  their  volume  of  boiling  water. 
Carbolic  acid  and  other  strong  disinfectants  should  also 
be  used  under  the  direction  of  a  doctor  or  a  trained 
nurse. 

Next  to  water,  milk  is  one  of  the  readiest  means  of 
scattering  typhoid  fever  germs.  The  germs  grow 
rapidly  in  milk  and  multiply  prodigiously,  while  in 
water  the  germs  do  not  multiply  but  tend  to  decrease 
in  numbers.  Besides,  milk  often  becomes  infected 
from  polluted  water.  Such  water  is  sometimes  used 
to  dilute  the  milk,  though  milk  is  less  likely  to  be 
adulterated  in  this  way  than  formerly.  Severe  out- 
breaks of  typhoid  fever  have  occurred  because  the  milk 
cans  were  washed  in  cold  water  which  contained  living 
typhoid  fever  germs. 

Many  persons  have  had  typhoid  fever  through  com- 
ing in  contact  with  other  persons  who  were  sick  with  the 
disease.  When  one  member  of  the  family  has  typhoid 
fever,  other  members  of  the  family  are  very  likely  to 
take  the  disease  from  him,  On  this  account,  a  person 


308  THE   BODY   IN   HEALTH 

who  has  this  disease  should  be  isolated  ;  that  is,  no  one 
should  be  allowed  to  come  in  contact  with  the  sick 
person  except  the  physician  and  nurses. 

Nearly  half  of  all  the  cases  of  typhoid  fever  contracted 
from  milk  owe  their  origin  to  typhoid  fever  carriers  ; 
that  is,  persons  who  have  had  typhoid  fever  and  who 
have  recovered  from  the  disease  without  getting  rid 
of  the  germs.  Such  persons  may  carry  the  germs  with 
them  for  many  years,  and  are  constantly  infecting 
persons  and  things  with  which  they  come  in  contact. 

In  the  State  of  New  York,  it  was  found  that  nearly 
half  of  all  the  cases  of  infection  through  milk  were  due 
to  typhoid  carriers  by  whom  the  milk  was  handled.  On 
this  account  it  is  very  important  that  all  milk  dealers 
should  be  carefully  examined  to  determine  whether  or 
not  they  are  carriers.  Such  an  examination  is  required 
by  law  in  many  states. 

Fresh  vegetables  such  as  lettuce,  celery,  and  cabbage, 
also  strawberries,  may  be  infected  with  typhoid  through 
the  use  of  night  soil  as  a  fertilizer.  It  has  recently 
been  found  that  plants  growing  in  a  soil  which  had  been 
infected  with  typhoid  germs  previous  to  planting  are 
liable  to  become  contaminated  and  may  communicate 
the  disease. 

Within  recent  years  a  method  of  vaccinating  against 
typhoid  fever  has  been  perfected,  and  by  the  means  of 
this  anti-typhoid  vaccine  many  thousands  of  lives  were 
saved  during  the  great  European  war.  It  is  known, 
however,  that  vaccine  is  not  a  perfect  protection,  so 


"CATCHING"  DISEASES  309 

that  a  vaccinated  person  should  not  neglect  any  of  the 
precautions  which  have  been  above  suggested. 

The  new  vaccine  has  been  successfully  used  in  the 
treatment  of  typhoid  carriers  to  free  them  from  the 
dangerous  germs. 

Some  physicians  recommend  that  all  persons  who 
are  compelled  to  come  in  contact  with  persons  sick 
with  typhoid  fever  should  be  vaccinated  against  the 
disease.  Vaccination  if  properly  done  not  only  renders 
a  person  much  less  likely  to  suffer  from  the  disease  but 
greatly  lessens  the  severity  of  the  disease  if  an  attack 
occurs. 

It  is  highly  important  that  typhoid  carriers,  as  well 
as  other  germ  carriers,  should  be  kept  from  contact 
with  other  persons  until  free  from  germs.  A  case  was 
recently  reported  in  which  nineteen  persons  suffered 
from  typhoid  after  partaking  of  turkey  salad  which 
had  been  prepared  by  a  carrier. 

Dysentery  and  fevers  closely  allied  to  typhoid  fever 
are  also  produced  by  polluted  water  and  infected 
foods. 

Diphtheria  is  sometimes  communicated  by  milk 
which  becomes  infected  through  the  coughing  and 
sneezing  of  diphtheria  carriers  engaged  in  handling  .the 
milk. 

Infectious  diseases  which  are  accompanied  by  an 
eruption,  such  as  measles  and  scarlet  fever,  are  un- 
fortunately most  contagious  just  before  the  erup- 
tion appears,  so  that  many  persons  are  likely  to  be 


3io  THE   BODY  IN  HEALTH 

exposed  before  the  danger  is  easily  recognizable.  On 
this  account,  all  schools,  armies,  and  great  industrial 
institutions  should  be  under  constant  and  careful 
medical  supervision  so  that  the  very  beginnings  of  dis- 
ease may  be  recognized. 

During  epidemics  of  infectious  diseases  one  should 
spend  as  much  time  as  possible  in  the  open  air,  should 
sleep  with  windows  widely  open  or  on  a  sleeping  porch, 
and  should  avoid  crowds  and  physical  contacts,  even 
"handshaking"  as  much  as  possible. 

Why  is  one  less  likely  to  take  an  infectious  disease  in 
the  open  air  than  in  the  house  ? 

HEALTH  PROBLEMS 

1.  Have  you  or  your  family  ever   been   quarantined?     If  so, 
for  what  reason  ?     How  did  you  communicate  with  the  outside 
world  during  the  quarantine  ?     Did  you  feel   at  the  time  that 
you  were  unjustly  treated  ? 

2.  Are  pupils  ever  kept  out  of  your  school  on  account  of  ill- 
ness ?     Who  forbids  them  to  come  to  school  ? 

3.  Have  you  known  of  pupils  who  have  come  to  school  with 
contagious  diseases  and  have  given  them  to  other  pupils  ?     Was 
this  fair  to  the  well  pupils  ? 

4.  Sometimes   when   a  contagious    disease   gets   started  in   a 
school,  the  school  board  closes  the  school  for  a  week  or  more. 
Why? 

5.  Have  you   been  vaccinated?     What  good  does  vaccination 
do? 

6.  Have  you  known  of  any  person  who  has  been  given  anti- 
toxin ?     If  so,  for  what  reason  was  it  given  to  him  ?     Do  you  know 
whether  it  helped  him  ? 


"CATCHING"   DISEASES  311 

7.  If  you   can   do   so,   find   out   how   antitoxin   is   prepared. 
Your  family  physician  should  be  able  to  tell  you. 

8.  If  two  people  are  exposed  to  diphtheria  in  the  same  way, 
one  may  catch  it  and  the  other  may  not.     Why  is  this  so  ? 

9.  Is  there  a  medical  inspector  who  visits  your  school  ?     If 
so,  state  just  what  he  does.     If  there  is  no  such  inspector,  do  you 
think  one  ought  to  be  appointed  ?     Why  ? 

10.  In  some  schools  they  have  a  "visiting  nurse"  who  goes 
into  all  the  rooms  every  day  and  takes  a  look  at  all  the  pupils. 
If  she  suspects  any  one  of  having  a  contagious  disease,  she  makes 
a  special  examination  to  find  out  for  sure.     Do  you  think  such  a 
visiting  nurse  would  be  a  help  to  your  school  ?     Why  ? 

11.  Have  you  ever  heard  of  a  person's  being  immune  to  certain 
diseases,  such  as  whooping  cough  ?     What  does  this  mean  ?     How 
is  it  possible  ? 

REVIEW  QUESTIONS 

1.  What  is  the  meaning  of  communicable  diseases  ? 

2.  Mention  some  common  communicable  diseases. 

3.  Might  a  person  who  has  one  of  these  diseases,  but  who  is 
not  very  sick,  be  a  danger  to  other  people,  if  he  should  play  or 
study  with  them  ?     Why  ? 

4.  What  does  it  mean  to  be  put  in  quarantine?     Who  is  it 
in  a  community  that  puts  a  person  with  a  contagious  disease  in 
quarantine  ? 

5.  What  diseases  may  one  be  getting  when  his  throat  begins 
to  feel  sore  ? 

6.  How  does  a  physician  make  a  test  for  diphtheria  ? 

7.  When  is  a  thing  sterile?     How  can  one  make  a  spoon,  for 
instance,  sterile  ? 

8.  What  is  the  meaning  of  a  culture?     How  does  a  physician 
make  a  culture  of  diphtheria,  for  instance  ? 

9.  What  does  antitoxin  do  in  the  body  ? 

10.  Has  antitoxin  saved  the  lives  of  many  people  ? 


3i2  THE   BODY   IN  HEALTH 

11.  May  a  person  carry  the  germs  of  diphtheria,  even  if  he  is 
not  sick  himself? 

12.  Why  did  the  health  authorities  put  a  placard  on  the  door 
of  Georgia's  house,  warning  people  not  to  enter  ? 

13.  Why  did  they  forbid  all  the  people  in  the  house  from  going 
out  on  the  street  ? 

14.  What  did  they  put  on  the  poster   which  they  placed  in- 
doors ?     Why  is  it  necessary  to  give  these  directions  to  a  family  ? 

15.  How  does  a  nurse  disinfect  the   articles   used    by  a  sick 
person  ?     Why  was  it  necessary  to  be  so  careful  about  this  ? 

16.  How   do   people    get   the    diphtheria    germs   which    cause 
sickness? 

17.  WThy  are  people  often  so  careless  about  sending  out  letters 
and  the  like  from  those  who  are  sick  with  contagious  diseases  ? 

1 8.  In  an  earlier  day,  did  people  think  children  ought  to  get 
all  the  "catching"  diseases  ?     Why  ? 


APPENDIX 


TABLES   OF   COMPOSITION  OF   FOODS 

You  should  keep  the  following  tables  for  reference, 
so  that  you  can  tell  what  nutrients  are  to  be  found  in 
all  the  ordinary  foods.  The  meaning  of  the  figures  in 
these  tables  is  clear  when  you  remember  that  for  every 
100  Ib.  of  milk,  eggs,  etc.,  87.0  Ib.  is  water,  3.3  Ib.  is 
protein,  etc. 

PROTEIN  FOODS  —  COMPOSITION 


FOOD 

WATER 

PROTEIN 

FAT 

CARBOHY- 
DRATES 

ASH 

MINERAL 

Milk           .... 

87.O 

3.3 

4..O 

c.O 

O.7 

Effffs 

7-2.7 

14.8 

IO.  S 

O.O 

I.O 

Cheese       .... 
Fowl     

34-0 
63.7 

24.3 

10-3 

33-4 
16.3 

4-5 

O.O 

3.8 

I.O 

Beef     

6l.Q 

18.6 

i8.q 

O.O 

I.O 

Fish  (lean)     .     .     . 

82.6 

15.8 

•4 

0.0 

1.2 

U.  S.  Department  of  Agriculture. 


GENERAL  COMPOSITION  OF  GRAINS 


GRAINS 

WATER 

PROTEIN 

FAT 

CARBO- 
HY- 
DRATES 

CELLU- 
LOSE 

ASH 
MINERAL 

Bread,  Graham  (whole  meal) 
IVlacaroni            .... 

357 
it  i 

8.9 
Q  O 

1.8 

O.3 

S2.I 
768 

I.I 

i-S 

0.8 

Wheat      

II.  A. 

13.8 

I.Q 

71.0 

.0 

I.O 

7.3 

16.1 

7.2 

67.  c 

O.O 

I.O 

Barley       

II.  e 

8.c 

I.I 

77.8 

O.3 

I.I 

Corn  (green)      

7C.4. 

3.1 

I  I 

IQ  7 

O  5 

O.7 

Rice 

0.3 

8.0 

0.3 

7Q.O 

O.2 

0.4. 

313 


APPENDIX 


GENERAL  COMPOSITION  OF  FRUITS 


EDIBLE  PORTION  FRUIT 

WATER 

PROTEIN 

FAT 

CARBOHY- 

DBATES 

CELLU- 
LOSE 

ASH 
MINERAL 

Gooseberries 

8S.6 

I.O 

T  -J     T 

O  3 

8q.o 

I.C 

1  J'1 

12  8 

*i**j 

O  7 

Whortleberries  

82.4 

O.7 

7.O 

T-7  r 

?  2 

O  4. 

Blueberries  \ 

88  o 

OA 

O6 

*  J'j 

j«« 

Cranberries  J 
Grapes      

77.4. 

•4 
1.1 

1.6 

9.9 

IQ  2 

»»s 

4-7 

O  1 

Blackberries 

86  3 

I.-j 

I.O 

in  Q 

2  C 

***3 

O  C 

84.1 

1.7 

I.O 

i^.y 
12.6 

*»3 

"•3 

0.6 

Strawberries       

OO.4 

I.O 

0.6 

7  4. 

I  4. 

06 

Melons 

80.  c 

0.6 

9-7 

2  I 

06 

O2.4 

0.4 

O.2 

6.7 

O.'? 

Pineapples     

89.1 

O.4 

0.3 

O.7 

O.4 

o.i 

Bananas    

7C.-I 

I,  -i 

0.6 

22  O 

I  O 

o  8 

84.6 

O.4 

o.q 

14.2 

1.2 

O.1? 

Pears    

84.4 

0.6 

o.c. 

1  4.  1 

'  2.7 

O.4 

Peaches     

8o.4 

O.7 

O.I 

9.4 

1.6 

O.4 

Plums 

78  4 

I.O 

2O  I 

O  C 

Cherries    

8o.Q 

I.O 

0.8 

l6.7 

O.2 

0.6 

Oranges    

86.9 

0.8 

O.2 

n.6 

c.c 

Dates  (dried) 

1C   A 

2.1 

2.8 

78  4 

I.I 

Figs  (dried) 

18  8 

4-5 

O  3 

74.  2 

2  J. 

Prunes  (dried)    
Raisins  (dried) 

22.3 
146 

•3 

2.1 
2.6 

-3.-J 

f  T** 

73-3 
76.1 

2-3 
•1.4, 

Olives 

67  o 

2  £ 

Q  O 

4.4 

THE  COMPOSITION  OF  LEGUMES 


LEGUMES 

WATER 

PROTEIN 

FAT 

CARBO- 
HY- 
DRATES 

CELLU- 
LOSE 

ASH 
MINERAL 

Lima  beans  (dried)     .     .     . 
String  beans       

10.4 

8Q.2 

18.1 

2  1 

i-5 

•7 

65-9 

7     A 

I  Q 

4.1 
g 

Green  peas 

746 

7  n 

e 

•T- 

16  Q 

i.y 
I  7 

I  O 

Peas  (dried)  

o.e 

24.6 

o 
I  O 

6^  o 

*•/ 

4r 

2  Q 

Lentils  (dried)    

8.4 

2C  7 

I  O 

CQ  2 

O 

57 

Beans  (dried) 

126 

22  C 

i  8 

JV"*' 

co  6 

4j^ 

•/ 
•j    C 

*»o 

5V-U 

•T1 

J'3 

APPENDIX 


GENERAL  COMPOSITION  OF  NUTS 


EDIBLE  PORTION  NUTS 

WATER 

PROTEIN 

FAT 

CARBO- 
HY- 
DRATES 

CELLU- 
LOSE 

ASH 
MINERAL 

Cocoanuts 

Ml 

r  7 

en  6 

27  Q 

I  7 

Almonds 

4.  8 

;>•/ 
21  O 

CA  Q 

17  3 

*>  o 

2  O 

T"* 

2.7 

06 

;>T-y 
70.  c 

I  C.'? 

I.Q 

Hickory  nuts      

4.7 

I  C  4. 

67.4. 

II.  4. 

2.1 

Filberts          

-j  7 

je  6 

6C   7 

I-j  o 

2  4. 

Brazil  nuts 

C    •? 

17  O 

66  8 

7  O 

-7    Q 

Chestnuts 

AC  O 

6  2 

54 

4.2  I 

i  8 

J'V 
I    1 

Walnuts  (black)      .... 
Peanuts     

TO''"' 

2-5 
Q.2 

27.6 
2C  8 

•T- 

56.3 

<?8.6 

T-*"i 
II.7 
24.  4. 

i-7 

2.C 

»«J 

1.9 

2  O 

GENERAL  COMPOSITION  OF  VEGETABLES 


EDIBLE  PORTION  VEGETABLES 

WATER 

PROTEIN 

FAT 

CARBO- 
HY- 
DRATES 

CELLU- 
LOSE 

ASH 
MINERAL 

Potatoes   .     

78  -? 

2.2 

O  I 

18.4 

O.4. 

.O 

Sweet  potatoes 

60  o 

8 

O  7 

27  4. 

I  ^ 

I 

Carrots     

88.2 

.1 

O.4. 

Q.-I 

I.I 

.O 

Turnips     

80.6 

.7 

O  2 

8  i 

I.I 

0.8 

Radishes  ....          . 

QI  8 

.-7 

O  I 

c  8 

O.7 

.0 

Beets 

87  c 

6 

O  I 

Q  7 

O  Q 

,i 

Parsnips    

8<?.o 

.6 

o.c 

I-i.tr 

2.C 

.4. 

Cabbage   

QI  1 

.6 

o  ^ 

c.6 

I.I 

.0 

Cauliflower    ... 

O2  3 

g 

o  c 

47 

I.I 

O.7 

Spinach     .          

Q2.1 

.1 

**o 

O.7 

-2.2 

O.Q 

2.1 

QA.  C 

.1 

O  I 

•5    -2 

O.I 

Asparagus     

Q4.  O 

8 

O  2 

-J    -J 

0.8 

O.7 

Cucumber      

QC    A 

08 

O  2 

•7    T 

O.7 

o.c 

yj-*r 

QJ.  7 

O.Q 

.4. 

-7.Q 

0.6 

O.C. 

88  -? 

1.4. 

O  5 

O.O 

0.8 

0.8 

Onions      

876 

i  6 

O  "? 

O  Q 

0.8 

0.6 

APPENDIX 


GENERAL  COMPOSITION  OF  FATS 


FATS 

WATER 

PROTEID 

FAT 

CARBO- 
HYDRATES 

ASH 

MINERAL 

Butter       .... 

II.O 

I.O 

85.0 

3-0 

Olive  oil    .     .     .     . 

1  00.0 

Cream       .... 

74.0 

2.5 

18.5 

4-5 

o-S 

AVERAGE  COMPOSITION  OF  FOODS 


FRUIT 

NUTS 

LEGUMES 

Water       

8r_Qo% 

d.-S% 

10-14.20% 

Proteid 

c% 

I  $—2O% 

13.  81-25.16% 

Fat       . 

.05  % 

50-60% 

0.58-2.46% 

Carbohydrates  .... 
Cellulose  

5*-ioJ% 

2\% 

9-12% 
3-c% 

52-12% 
2~3  % 

Mineral  matter  ...... 

•05% 

1% 

GLOSSARY 

KEY  TO  PRONUNCIATION 

a,  as  in  ale;  &,  as  in  sen/ate;  a,  as  in  care;  3,  as  in  am;  a,  as  in  arm;  a,  as 
in  ask;  a,  as  in  fi'nal;  e,  as  in  eve;  e,  as  in  e-vent';  e,  as  in  end;  e,  as  in  fern; 
f,  as  in  re'c^nt;  I,  as  in  ice;  i,  as  in  i-de'a;  I,  as  in  ill;  o,  as  in  old;  6,  as  in 
6-bey';  6,  as  in  Qrb;  6,  as  in  odd;  u,  as  in  use;  u,  as  in  u-nite';  tt,  as  in  tip; 
U,  as  in  urn;  y",  as  in  pit' y;  oo,  as  in  food;  do,  as  in  foot;  ou,  as  in  out;  ol,  as 
in  oil. 


abdominal  cavity  (ab-dom'i-nal  kaVi-ty).     The  hollow  place  in  the  body 

in  which  the  organs  of  the  abdomen  are. 
abscess  (ab'ses).     A  collection  of  pus  in  any  tissue  or  organ  of  the  body, 

due  to  infection, 
adenoids  (ad'e-noids).     Growths  that  form   in  the  nasal   passages  and 

interfere  with  breathing, 
albumen  (al-bu'men).     One  element  of  food,  found  in  the  white  of  an 

egg,  for  instance, 
alimentary  canal  (al'i-men'ta-ry  ka-nal').      The  whole  length  of  the  food 

channel  extending  through  the  body, 
alkalinity  (aTka-lin'i-ty).     Having  the  quality  of  an  alkaline  substance, 

like  soda,  for  instance. 

amoeba  (a-me'ba).     A  tiny  animal  that  consists  of  just  one  cell, 
analogous  (a-naFo-gus).     Having  a  likeness  to  something  else, 
anterior  chamber  (an-te'ri-er  cham'ber).     The  enclosed  space  in  the  eye 

in  front  of  the  lens, 
anvil  (an'vil).     One  of  the  three  small  bones  in  the  ear.     This  bone  has  a 

shape  like  that  of  a  blacksmith's  anvil. 

apex  (a'peks).     The  tip,  point,  of  anything;   as  the  apex  of  the  heart, 
apoplexy   (ap'6-pleks'y).     The   pressure   of    blood   in   the   brain,   which 

causes  a  blood  vessel  to  burst, 
aqueous  humor  (a'kwe-iis  hu'mer).      A  fluid  in  the  eye  which  fills  the 

anterior  chamber, 
assimilation  (as-sim'i-la'shun).     The     process   of    changing    blood    into 

tissues  and  organs, 
auditory  canal  (a/di-to-ry  ka-naT).     The  tube  from  the  opening  of  the 

ear  to  the  drum  of  the  ear. 


318  GLOSSARY 

auricle  (a/ri-k'l).  One  of  the  compartments  in  the  heart,  that  receives 
the  blood  from  the  veins.  Its  name  comes  from  its  likeness  to  the 
outside  ear. 

B 

bacteria   (bak-te'ri-a).     (The   plural   of  bacterium.)     Tiny   plants  that 

grow  in  the  body.     Some  are  harmful ;  some  helpful, 
biconcave  disks  (bi-kon'kav  disks).     Round  plates  hollowing  in  on  both 

sides  at  the  center, 
bicuspids  (bi-kus'pids).     The  two  double-pointed  teeth  which  grow,  one 

on  each  side  of  the  jaw,  between  the  cuspids  and  the  molars. 
bile  (bil).     A  yellow  or  greenish  fluid  found  in  the  liver;   gall, 
biliousness  (bil'yus-nes).     The  state  of  the  body  when  there  is  too  much 

bile  in  the  system, 
bismuth  (biz'muth).     A  substance  used  sometimes  to  observe  the  course 

which  food  takes  in  the  alimentary  canal. 
bronchi  (bron'ki).     (The  plural  of  bronchus.)     The  tubes  that  carry  the 

air  from  the  windpipe  into  the  lungs. 
bronchioles  (bron'ki-oles).     Tiny  bronchial  tubes. 


capillary  (kap'il-la-ry  or  ka-pil'la-ry).     A  tiny,  thin-walled  tube;   partic- 
ularly one   of  the  smallest   blood  vessels   connecting   arteries  and 

veins, 
carbohydrates   (kar'bo-hl'drats).     Food    elements    including    principally 

sugar  and  starches. 
carbonic  acid  gas  (kar-bon'ik  as'id  gas).      The  substance  which  a  plant 

takes  from  the  air,  and  which  is  thrown  off  from  the  lungs  of  animals 

in  breathing. 

cardiac  (kar'di-ak).     Pertaining  to  the  heart, 
cartilage  (kar'ti-laj).     An  elastic  tissue  found  mainly  in  the  body  between 

joints  and  at  the  ends  of  bones, 
cell  (sel).     One  of  the  tiny  structures  that  compose  the  greater  part  of 

the  tissues  and  organs  in  the  body, 
cellulose  (sel'u-los')-     One  of  the  envelopes  formed  of  a  woody  substance 

that  encloses  starch, 
cerebellum  (ser'e-bel'lum).     The  little  brain.     It  controls  the  action  of 

the  muscles, 
cerebrum  (ser'e-brum).     The  larger  division  of  the  brain.     It  controls 

reasoning  and  willing. 

choroid  (ko'roid).     The  middle  coat  of  the  eyeball, 
chyme  (kim).     The  name  given  to  the  food  we  have  eaten  when  it  is  a 

half-digested  pulpy  mass.      The  food  is  in  this  state  in  the  small 

intestines. 


GLOSSARY  319 

cilia  (sil'i-a).     (The  plural  of  cilium,  which  is  rarely  used.)     Tiny  hairs 

in  the  air  passages. 

clot  (klot).     A  thickened  congealed  mass,  as  a  clot  of  blood, 
cochlea  (kok'le-a).     The  part  of  the  ear  at  the  entrance  of  the  inner  ear. 
colic  (kol'ik).     A  severe  pain  in  the  abdomen, 
colon  (ko'lon).     A  part  of  the  large  intestine, 
combustion  (kom-bus'chun).     The  process  of  burning, 
contaminated  (kon-tam'i-na'ted).     Made  foul ;  polluted ;  stained ;  soiled; 

dangerous,   as  when   milk  or  water  is   contaminated   by  germs  of 

typhoid  or  other  diseases, 
convolutions   (kon'vo-lu'shunz).     Irregular  winding  folds    of  an  organ; 

as  the  convolutions  of  the  brain  ;  the  convolutions  of  the  intestines, 
cornea  (kor'ne-a).     The  part  of  the  coat  of  the  eyeball  which  covers  the 

iris  and  the  pupil  and  lets  in  light  to  the  inside  of  the  eye. 
cranium  (kra'ni-um).     The  skull;  the  bony  case  for  the  brain, 
crystalline  lens  (kris'tal-lln  or  -1m  lenz).     The  part  of  the  eye  that  brings 

the  rays  of  light  to  a  point, 
cuspids  (kus'pidz).     The  teeth  that  have  but  one  point  (or  cusp)  on  the 

crown. 

D 

dermis  (der'mis).     The  layer  of  skin  beneath  the  scarfskin  or  epidermis, 
diaphragm  (di'a-fram).      The  muscle  that  separates  the  cavity  of  the 

chest  from  that  of  the  abdomen, 
digestion  (di-jes'chun).      The   changing   of  foods    into    such    form    that 

the  blood  can  absorb  the  useful  parts  and  the  body  throw  off  the 

useless  parts. 

dilate  (di-laV  or  dl-lat').     To  enlarge,  to  swell;   to  expand, 
duct  (dukt).     A  tube  or  canal. 

E 

emulsified    (e-mul'si-fid).      Subdivided    into    tiny    particles,    as    when 

olive  oil  is  emulsified  in  lemon  juice, 
enzyme  (en'zim).     A   substance   made   by   the   salivary   glands,    which 

causes  fermenting,  and  is  necessary  for  the  digestion  of  starch, 
epidermis  (ep'i-der'mis).     The  outer  layer  of  the  skin,  the  scarfskin. 
epiglottis  (ep-i-glot'tis).     The  lid-like  covering  which  closes  the  glottis 

while  food  or  drink  passes  through  the  pharynx, 
epithelial   cells  (ep'i-the'li-al  selz).      Cells  that  cover  the  surface  of  the 

body  and  line  all  the  cavities  of  the  body. 

epithelium  (ep-i-the'li-um).     The  covering  formed  by  the  epithelial  cells, 
esophagus  (e-sof'a-gus).     The  part  of  the  alimentary  canal  between  the 

pharynx  and  the  stomach;    the  gullet, 
eustachian  tube  (u-sta'ki-an  tub).     The  tube  that  leads  from  the  ear  drum 

to  the  pharynx, 
excretion  (eks-kre'shun).     The  act  of  throwing  off,  of  discharging  wastes 

from  the  body. 


320  GLOSSARY 


fiber  (fi'ber).     A  delicate   threadlike    substance;    especially  the  slender 
tissues  which  form  muscular  tissues. 


gall  bladder  (gal  blad'der).     The  sac  in  which  the  bile,  or  gall,  is  stored 

up. 
gastric  juice  (gas'trik  jus).     A  thin  watery  fluid  of  an  acid  nature  that 

flows  from  the  walls  of  the  stomach  to  mix  with  the  food  and  aid 

digestion. 

germicide  (jer'mi-sid).     Anything  that  kills  germs, 
glottis  (glot'tis).     The  opening  from  the  pharynx  into  the  larynx  or  into 

the  trachea. 

glycogen  (gli'ko-jen).     Digested  starch  stored  in  the  body, 
gossamer  (gos'sa-mer).     Any  very  thin  gauzelike   fabric;    a  fine,  filmy 

substance  like  cobwebs. 

granule  (gran'ul).     A  little  grain;    a  small  particle;    a  pellet, 
gullet  (gul'let).     The  tube  by  which  food  is  carried  from  the  pharynx 

to  the  stomach;    the  esophagus. 


hair  follicle  (har  fol'li-k'l).     A  small  cavity,  or  depression,  at  the  outer 

end  of  a  tiny  tube,  from  which  a  hair  grows, 
hammer  (ham'mer).     One  of  the  three  small  bones  in  the  ear.     It  gets 

its  name  from  its  likeness  to  a  hammer, 
hemoglobin  (hem'6-globin   or   he'mo-glo'bin).      The  coloring  matter  of 

the  red  blood  corpuscles. 
hydrochloric  acid  (hi'dro-klo'rik  as'id).     An  acid  contained  in  the  gastric 

juice. 

incisors  (in-si'zerz) .     The  teeth  in  front  of  the  canines,  or  cuspids.     They 

are  used  especially  for  cutting  food. 

inorganic  (m'or-gan'ik).     Without  the  organs  necessary  for  life;  lifeless. 
insoluble   (m-sol'u-b'l).     Incapable  of  being  dissolved   as   by  a  liquid, 

as  chalk  is  insoluble  in  water, 
intestines  (in-tes'tinz).     All  of  the  alimentary  canal  from  the  stomach 

on  down, 
iris   (I'ris).     The  movable,  muscular  curtain    lined  with  dark  pigment 

found  in  the  eye. 

jaundice  (jan'dis).     A  disease  in  which  the  eyes  and  skin  turn  yellow 
for  one  thing. 


GLOSSARY  321 

L 

lachrymal  gland  (lak'ri-mal  gland).     The  gland  in  which  tears  are  formed. 

lacteals  (lak'te-alz).  The  small  vessels  which  carry  a  milky  fluid  con- 
taining fatty  matter  from  the  small  intestine. 

larynx  (lar'inks).     The  entrance  to  the  windpipe. 

ligaments  (lig'a-ments).  Bands  of  strong  connective  tissue  which  unite 
bones  and  form  joints. 

liver  (liv'er).  The  organ,  lying  near  the  stomach,  which  manufactures 
bile. 

lubricated  (lu'bri-ka-ted).  To  make  smooth  or  slippery  (in  order  to  cause 
to  work  without  grating  or  frict,°oin,. 

lymph  (limf).  The  part  of  the  blood  that  leaks  from  the  blood  vessels. 
It  contains  no  red  blood  corpuscles. 


maltose  (malt/os).     A  crystalline   sugar  called    malt  sugar  or  maltose, 

derived  from  grains. 

mastication  (mas'ti-ka'shun).     Chewing;  as  mastication  of  food, 
medulla  (me-dul'la).     An  expansion  of  the  upper  end  of  the  spinal  cord, 

which  controls  such  reflex  acts  as  breathing  and  the  beating  of  the 

heart, 
microbes  (microbes  or  mik'robes).     An  organism  so  small  that  it  cannot 

be  seen  by  the  naked  eye. 
microscope  (mi'kro-skop  or  mik'ro-skop).     An  instrument  by  which  the 

eye  is  enabled  to  see  organisms  too  small  to  be  seen  without  aid. 
molars  (mo'lerz).     Any  of  the  teeth  back  of  the  incisors  and  canines, 

used  for  grinding  food, 
mucous  membrane  (mu'kus  mem'bran).     The  thin  layer  of  tissue  lining 

the  passages  and  cavities  of  the  body. 

N 

neuron  (nu'ron).     A  nerve  cell  with  its  branches. 

nitrogenous  foods  (ni-troj'e-nus  foodz).     Foods  which  contain  the 

stance  known  as  nitrogen, 
nucleus  (nu'kle-us).     The  center  of  a  cell, 
nutrient  (nu'tn-ent).     Any  food  which   nourishes. 


olfactory   nerves   (61-fak'to-ry   nervz).     The   nerves   in   the   nose   upon 

which  smell  depends. 
optic  nerve  (op'tik  nerv).     The  nerve  from  the  eye  to  the  brain  upon 

which  sight  depends. 


322  GLOSSARY 

organic  (or-gan'ik).     A  thing  having  organs;   alive. 
osseous  tissue  (6s'se-us  tish'u).     Tissue  like  bone;   hard  tissue, 
oxygen  (oks'i-jen).     A  substance  necessary  to  life,  which  the  body  takes 
in  from  the  air. 

P 

palate    (pal' at).     The    hanging    partition    which    separates    the    mouth 

from  the  pharynx, 
pancreas  (pan'kre-as).     An  organ  near  the  stomach,  in  which  a  juice 

called  pancreatic  juice  is  formed  to  aid  in  digestion, 
papillae  (pa-pil'le).     Tiny  moundlike  projections  of  the  skin. 
pepsin  (pep'sin).     One  of  the  fluids  composing  the  gastric  juice. 
peptone  (pep'ton).     Fluid  which  is  found  in  the  gastric  juice. 
periosteum     (per'i-os'te-um).     The    membrane    of    fibrous    connective 

tissue  that  covers  all  bones  except  at  the  joints. 
peristaltic    movements    (per'i-stal'tik    mooVments).     Peculiar  wormlike 

wave  motion  of  the  intestines  causing  the  food  to  move  on. 
phagocytes  (fag'o-sites).     White  blood  cells  that  act  as  germ  destroyers 

in  the  body, 
pharynx    (far'inks).     The    part   of  the    alimentary   canal    between   the 

mouth  and  the  esophagus. 

plasma  (plaz'ma).     The  fluid  part  of  the  blood  in  which  the  cells  float. 
posterior  chamber  (pos-te'ri-er  cham'ber).     The  enclosed  space   in  the 

eye  behind  the  lens. 

protein  (pro'te-in).     One  of  the  class  of  nutrients  which  furnishes  build- 
ing material  for  the  body. 
protozoa  (pr6'to-z5'a).     Tiny  animals  that  grow  in  the  body  and  cause 

disease. 

pupil  (pu'pil).     The  opening  of  the  eye,  in  the  center  of  the  iris, 
pus  (pus).     A  collection  of  dead  white  cells, 
putrefy  (pu'tre-fl).     To  decay;    to  rot. 
pylorus  (pl-lo'rus).     The  opening  of  the  stomach  into  the  intestine. 


rennin    (ren'nm).     One  of  the  fluids  composing  the  gastric  juice, 
respiration   (res'pi-ra'shun).     The  act  of  breathing, 
retina  (ret'i-na).     The  inner  coat  of  the  eyeball  containing  the  nerve  cells 
and  fibers  necessary  for  sight. 

S 

saliva  (sa-li'va).  The  fluid  found  in  the  mouth  and  manufactured  in 
the  salivary  glands;  necessary  for  the  digestion  of  starch. 

salivary  glands  (sal'i-va-ry  glandz).  Tiny  sacs  in  the  lining  of  the  mouth 
that  produce  the  fluid  called  saliva. 


GLOSSARY  323 

scavenger  (skav'en-jer).     One  who  cleans,  removes  waste,  makes  things 

healthy  by  removing  dirt  and  germs  that  breed  disease, 
sclerotic  (skle'-rot'ik).     The  outer  coat  of  the  eye. 
sebaceous  (se-ba'shus).     Composed  of  fat;    containing  fat. 
sedentary  (sed'en-ta-ry).     Inactive  physically;    requiring  much  sitting, 
septum  (sep'tum).     A  partition  separating  the  nostrils  or  nasal  cavity 

into  two  parts, 
serum  (se'rum).     The  pale  yellowish  fluid  that  comes  .out  from  a  clot  of 

blood. 

spasmodic  (spaz-mod'ik).     Convulsive,  irregular,  jerky,  uneven, 
spirometer  (spi-rom'e-ter).     An  instrument  for  measuring  the  capacity 

of  the  lungs, 
stagnant  (stag'nant).     Not  flowing;    motionless,  as  stagnant  water  in 

a  ditch, 
stimulus  (stim'u-lus).     Something  that  rouses  to  action,  as  stimulus  to 

sight  or  hearing  or  taste, 
stirrup  (ster'rup).     One  of  the  three  small  bones  of  the  ear.     It  gets  its 

name  from  its  shape, 
stomach  (stum'ak).     The  cavity  in  the  body  made  by  the  enlargement 

of  the  alimentary  canal,  which  lies  above  the  intestines, 
suspensory  ligament  (sus-pen'so-ry  lig'a-ment).     A  suspended  or  hanging 

band  of  connective  tissue, 
symmetrical    (sim-met'ri-kal).     Having   one    side    like    another;     even, 

regular. 

T 

thoracic  duct  (tho-ras'ik  dukt).     The  great  trunk  of  the  lymphatic  vessels, 

between  the  intestines  and  the  heart, 
thorax  (tho'raks).     The  part  of  the  trunk    between  the  neck  and  the 

abdomen, 
tissue  (tish'u).     The  fibers  that  go  to  make  up  organs  of  any  sort,  as  the 

heart  or  lungs, 
tonsil  (ton'sil).     One  of  the  two  organs  placed  on  each  side  of  the  throat, 

and  serving  to  destroy  germs  on  the  way  to  the  lungs, 
trachea  (tra'ke-a  or  tra-ke'a).     The  windpipe, 
tympanic  membrane  (tim-pan'ik  mem'bran).     The   delicate  skin  in  the 

ear  stretched  across  the  lower  end  of  the  canal.     It  is  called  the  drum. 

V 

ventricle  (ven'tri-k'l).  One  of  the  cavities  of  the  heart,  which  forces  the 
blood  from  the  heart  into  the  arteries. 

vertebrae  (ver'te-bre).  (Plural  of  vertebra.)  The  bones  of  the  spinal 
column. 

villi  (vil'li) .  (Plural  of  villus,  which  is  rarely  used.)  The  tiny,  fine,  finger- 
like  projections  which  cover  the  lining  of  the  stomach. 


INDEX 


Adenoids,  effect  of,  on  health,  126- 
127. 

Albumen,  in  eggs,  26. 

Alcohol,  effect  of,  on  cells,  29;  on 
heart,  106-107;  on  lungs,  129; 
on  kidneys,  145-146;  on  nervous 
system,  221-222;  enemy  of  the 
body,  269-279 ;  kills  living  things, 
270-271 ;  effects  on  the  human 
body,  271-274;  a  deceiver,  274. 

Alimentary  canal,  34-35;   54- 

Amoeba,  1-3. 

Arteries,  87. 

Athletics,  effect  of  excess  in,  107- 
108. 

Bile,  46. 

Blood,  74-99;  blood  cells,  75-79; 
defensive  and  healing  power  of 
blood  cells,  79;  phagocytes,  81 ; 
necessity  for  alkalinity  of  blood, 
82 ;  circulation  of,  83-96 ;  supply, 
how  controlled,  95-96;  keeping 
blood  in  good  condition,  loo-m. 

Body,  maintenance  of,  15-31;  how 
we  grow,  15-17;  how  cells  get 
their  energy,  17-20;  where  the 
material  in  the  body  comes  from, 
20-21 ;  plants  the  only  food 
producers,  21-22;  composition 
of  foods,  22-26 ;  uses  of  the  differ- 
ent foods,  26-29;  poisons,  the 
opposite  of  food,  29-30. 


Brain,  207,  211. 
Bronchial  tubes,  114-115. 

Carbohydrates,  22,  23-24;   uses  of, 

25- 

"Catching"  diseases,  294-307;  dan- 
ger of,  294;  quarantine,  294- 
295;  how  a  "culture"  is  taken, 
295-297;  antitoxins  and  their 
use,  297-299;  precautions  ob- 
served in  quarantine,  299;  an- 
imals may  carry  germs,  302-306. 

Cells,  1-13;  how  formed,  3-4; 
nucleus  of,  3 ;  colonies  or  com- 
munities of,  4;  cell  structures  or 
tissues,  6-10;  epithelial  cells,  8; 
gland  cells,  9-10;  groups  of  cells 
called  organs,  10-12;  effect  of 
alcohol  and  tobacco  on,  12-13; 
how  cells  get  energy,  17;  air 
cells,  114-116;  nerve  cells,  205- 
209. 

Cellulose,  in  foods,  22. 

Colds,  cause  of,  164;    cure  of,  165. 

Combustion,  to  produce  body  heat, 
16-17. 

Deformities,  how  caused,   186-187. 

Diaphragm,  122. 

Digestion,  first  step  in,  36;  im- 
portance of  teeth  for,  36;  in 
stomach,  40-45  ;  in  the  intestines, 
45-46;  work  of  the  liver,  52-53; 


325 


326 


INDEX 


depends  upon  enjoyment  of  food, 
59 ;  hindrances  to,  66-68 ;  as 
influenced  by  the  mind,  68. 

Digestive  juices,  35,  37,  42,  46,  47. 

Disease  germs,  enemies  of  the  body, 
280-293 ;  how  germs  enter  the 
body,  282 ;  how  the  body  defends 
itself,  283-286;  guarding  against 
disease,  286-287;  domestic  hy- 
giene,' 287-288 ;  personal  hygiene, 
288-289;  keeping  up  the  body's 
resistance,  289-290. 

Ear,  248-258;  how  we  hear,  249- 
250;  parts  of  the  ear,  250;  care 
of  the  ears,  254-255. 

Eating,  for  health  and  pleasure,  58- 
73 ;  digestion  depends  upon  en- 
joyment of  food,  59-60;  some 
causes  of  indigestion,  61 ;  a 
tired  stomach,  63  ;  hindrances  to 
digestion,  67;  how  digestion  is 
influenced  by  the  mind,  68;  the 
normal  guide,  70;  waste  in 
eating,  70-71. 

Enemies,  of  the  body,  269-279; 
280-293  ;  alcohol,  269-275 ;  to- 
bacco, 275-277;  disease  germs, 
280-293. 

Epidermis,  147-148. 

Esophagus,  39. 

Excretion,  organs  of,  141-153. 

Exercise,  to  strengthen  the.  heart, 
108-110. 

Eye,  228-247;  the  body's  camera, 
228-230;  the  protection  of,  230- 
23 1 ;  parts  of,  23 1 ;  the  way  we 
form  images  and  retain  them,  233  ; 
seeing  near  and  far  objects,  235- 
238;  wearing  glasses,  238;  with 


what  do  we  really  see  ?   238 ;   care 
of  the  eyes,  239-244. 

Fatigue,  cause  of,  198;  curing 
fatigue,  200;  after  effects  of,  201. 

Fats,  22,  24. 

Feeling,  and  thinking,  205-227; 
nerve  cells,  205,  209;  nerve 
fibers,  206;  spinal  cord,  207,  208, 
214;  brain,  207,  211;  sympa- 
thetic nervous  system,  208 ;  how 
we  feel  and  think,  208  ;  ingoing  and 
outgoing  nerves,  210;  brain  parts 
and  their  work,  212;  cerebellum, 
213;  cerebrum,  214;  medulla, 
214;  reflex  action,  215  ;  acquired 
reflexes,  216-218;  how  habits 
are  formed,  218;  how  we  remem- 
ber, 218;  how  to  have  a  clear 
head,  219-221 ;  nerve  poisons, 
221. 

Flushing,  cause  of,  159. 

Food,  source  of  body  energy,  17-18 ; 
material  for  building  tissues,  16; 
prepared  by  plants,  20;  common 
foods  rich  in  proteins,  fats,  and 
carbohydrates,  25 ;  how  food 
becomes  living  tissue,  33-57; 
food  canal,  34-35 ;  composition 
of,  308-311;  protein  foods,  308; 
grains,  308;  fruits,  309;  legumes, 
309;  nuts,  310;  vegetables,  310; 
fats,  311;  average  composition 
of  foods,  311. 

Framework,  of  the  body,  173-189; 
nature  and  uses  of  the  bones,  173- 
178;  good  bone-building  foods, 
173;  marrow,  176;  spinalcolumn, 
177;  vertebrae,  178;  joints,  179- 
181 ;  injuries  of  bones  and  joints, 


INDEX 


327 


181 ;  effect  of  tobacco  on  the 
bones,  182;  keeping  straight, 
182-186;  how  deformities  are 
caused,  186-187. 

Gastric  juice,  42-43  ;   59. 

Gland  cells,  9,  10. 

Glands,    salivary,    38;     lymphatic, 

92-93;    sweat  glands,  150-151. 
Grafting,  explanation  of,  5-6. 

Headache  remedies,  danger  of,  107. 

Hearing,  sense  of,  248-258. 

Heart,  83-86;  check  valves,  85; 
keeping  in  good  condition,  100- 
III ;  things  injurious  to,  104-108 ; 
alcohol  and  tobacco  injurious  to, 
106-107;  danger  of  headache 
remedies,  107;  how  to  strengthen 
the  heart,  124-128. 

Hunger,  explanation  of,  16. 

Hunter,  John,  results  of  experi- 
ments by,  74. 

Indigestion,  some  causes  of,  60-72. 
Intestine,  small,  45. 

Joints,  kinds  of,  180. 

Kidneys,  142-146;  alcohol  injuri- 
ous to,  145-146. 

Lacteals,  53. 

Larynx,  114,    134-136. 

Lime,  needed  in  food,  27. 

Liver,  work  of,  52-53. 

Lungs,  and  breathing  apparatus, 
113-139;  what  takes  place  in, 
119-123;  developing  the  capac- 


ity of,  129;   effect  of  alcohol  and 
tobacco  on,  129. 
Lymph,  92. 

Maltose,  24. 

Marrow,  of  the  bones,  176. 

Mastication,  36-38;   importance  of, 

60. 
Microbes,  work  of,  in  the  body,  5 1- 

52- 

Minerals,  needed  in  food,  27. 

Muscles,  of  the  body,  191-204; 
kinds  of,  192-194;  how  muscles 
are  attached  to  bones,  194; 
how  muscles  act,  195-197;  keep- 
ing muscle  tone,  197;  fatigue  of, 
198-202. 

Nerve  fibers,  205. 

Nervous  system,  205-227;  sym- 
pathetic nervous  system,  208; 
effect  of  alcohol  on,  221-222; 
effect  of  tobacco  on,  222-223. 

Neuron,  206. 

Nitrogen,  needed  for  cell  building, 
26. 

Nutrients,  definition  of,  22 ;  classes 
of,  22. 

Organs,  as  cell  groups,  10-12;  in 
health,  11-12;  effect  of  alcohol 
and  tobacco  on,  12-13. 

Oxygen,  essential  to  life,   113-114. 

Pancreatic  juice,  47-48. 

Pawlow,  experiments  of,  41-42 ;   59. 

Peristaltic  movement,  50. 

Phagocytes,  81. 

Pharynx,  117,  118. 

Plants,  as  food  producers,  20-22. 


328 


INDEX 


Plasma,  of  the  blood,  82. 
Poisons,  the  opposite  of  food,  29. 
Portal  circulation,  90. 
Proteins,  22,  24;   uses  of,  26-27. 
Pulmonary  circulation,  90. 
Pus,  how  formed,  80. 
Pylorus,  44-45. 

Reflex  action,  215;  acquired  re- 
flexes, 216-218. 

Saliva,  37-38. 

Salts,  in  foods,  22 ;  need  of,  27. 

Shivering,  cause  of,  158. 

Sight,  sense  of,  228-245  ;  the  body's 
camera,  228;  protection  of  eye, 
230-231;  forming  images,  233; 
use  of  glasses,  238;  with  what  do 
we  actually  see  ?  238. 

Skin,  uses  of,  146-151;  epidermis, 
147—148;  hair  and  nails,  148- 
149;  sweat  and  perspiration 
glands,  150-151. 

Smell,  sense  of,  259-261 ;  confusing 
smell  and  taste,  260-261 ;  destroy- 
ing the  sense  of  smell,  260. 

Spinal  column,  177. 

Spinal  cord,  207,  208,  214. 

Starch,  as  a  nutrient,  23. 

Stomach,  40-45 ;  a  tired  stomach, 
63-66. 

Sugar,  as  a  nutrient,  24. 

Sweat    glands,    work    of,    150-151. 

Systemic  circulation,  88. 

Taste,  sense  of,  261-263 ;  confusing 
smell  and  taste,  260-261 ;  as  a 
sentinel  of  the  body,  261-263. 

Teeth,  temporary,  36;  permanent, 
36. 


Temperature  of  the  body,  how  regu- 
lated, 155-172;  normal  tempera- 
ture, 155-156;  shivering,  cause 
of,  158;  flushing,  159;  work  of 
sweat  glands,  159-162;  tempera- 
ture in  fevers,  161 ;  effect  of  exer- 
cise on,  162;  effect  of  certain 
foods  on,  162;  effect  of  living  in 
heated  homes,  163  ;  colds,  cause 
of,  164;  saving  heat  loss  by 
clothing,  165-170. 

Tissues,  as  cell  structures,  6-10; 
white  fibrous  tissue,  7;  yellow 
elastic  tissue,  7;  adipose  tissue, 
7;  muscular  tissue,  8;  osseous 
tissue,  8 ;  cartilage  tissue,  8 ; 
nervous  tissue,  8;  how  food  be- 
comes living  tissue,  33-57;  mak- 
ing blood  into  tissues,  53—54. 

Tobacco,  effect  of,  on  cells,  29 ;  on 
heart,  106-107;  on  lungs,  129; 
on  vocal  cords,  136;  on  bones 
and  joints,  182;  on  nervous 
system,  222-223  '•>  a  cause  of 
disease,  275-277. 

Tonsils,  work  of,  117-118;  re- 
moval of,  in  disease,  118. 

Touch,  sense  of,  263-268;    sense  of 


temperature, 
pain,  265. 
Trachea,  114. 


264;     the    use    of 


Vertebrae,  178. 

Villi,  work  of,    in  digestion,  48-49. 

Vitamines,   in  food,   23. 

Vocal  cords,  134-136;  how  the 
voice  is  produced,  135  ;  change  of 
voice,  135  ;  injury  to  the  voice,  136. 

Water,  in  foods,  28. 


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